[ Upstream commit cb0e52b774 ]
We've noticed cases where tasks in a cgroup are stalled on memory but
there is little memory FULL pressure since tasks stay on the runqueue
in reclaim.
A simple example involves a single threaded program that keeps leaking
and touching large amounts of memory. It runs in a cgroup with swap
enabled, memory.high set at 10M and cpu.max ratio set at 5%. Though
there is significant CPU pressure and memory SOME, there is barely any
memory FULL since the task enters reclaim and stays on the runqueue.
However, this memory-bound task is effectively stalled on memory and
we expect memory FULL to match memory SOME in this scenario.
The code is confused about memstall && running, thinking there is a
stalled task and a productive task when there's only one task: a
reclaimer that's counted as both. To fix this, we redefine the
condition for PSI_MEM_FULL to check that all running tasks are in an
active memstall instead of checking that there are no running tasks.
case PSI_MEM_FULL:
- return unlikely(tasks[NR_MEMSTALL] && !tasks[NR_RUNNING]);
+ return unlikely(tasks[NR_MEMSTALL] &&
+ tasks[NR_RUNNING] == tasks[NR_MEMSTALL_RUNNING]);
This will capture reclaimers. It will also capture tasks that called
psi_memstall_enter() and are about to sleep, but this should be
negligible noise.
Signed-off-by: Brian Chen <brianchen118@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20211110213312.310243-1-brianchen118@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c86ff8c55b ]
Since commit db3a34e174 ("clocksource: Retry clock read if long delays
detected") and commit 2e27e793e2 ("clocksource: Reduce clocksource-skew
threshold"), it is found that tsc clocksource fallback to hpet can
sometimes happen on both Intel and AMD systems especially when they are
running stressful benchmarking workloads. Of the 23 systems tested with
a v5.14 kernel, 10 of them have switched to hpet clock source during
the test run.
The result of falling back to hpet is a drastic reduction of performance
when running benchmarks. For example, the fio performance tests can
drop up to 70% whereas the iperf3 performance can drop up to 80%.
4 hpet fallbacks happened during bootup. They were:
[ 8.749399] clocksource: timekeeping watchdog on CPU13: hpet read-back delay of 263750ns, attempt 4, marking unstable
[ 12.044610] clocksource: timekeeping watchdog on CPU19: hpet read-back delay of 186166ns, attempt 4, marking unstable
[ 17.336941] clocksource: timekeeping watchdog on CPU28: hpet read-back delay of 182291ns, attempt 4, marking unstable
[ 17.518565] clocksource: timekeeping watchdog on CPU34: hpet read-back delay of 252196ns, attempt 4, marking unstable
Other fallbacks happen when the systems were running stressful
benchmarks. For example:
[ 2685.867873] clocksource: timekeeping watchdog on CPU117: hpet read-back delay of 57269ns, attempt 4, marking unstable
[46215.471228] clocksource: timekeeping watchdog on CPU8: hpet read-back delay of 61460ns, attempt 4, marking unstable
Commit 2e27e793e2 ("clocksource: Reduce clocksource-skew threshold"),
changed the skew margin from 100us to 50us. I think this is too small
and can easily be exceeded when running some stressful workloads on a
thermally stressed system. So it is switched back to 100us.
Even a maximum skew margin of 100us may be too small in for some systems
when booting up especially if those systems are under thermal stress. To
eliminate the case that the large skew is due to the system being too
busy slowing down the reading of both the watchdog and the clocksource,
an extra consecutive read of watchdog clock is being done to check this.
The consecutive watchdog read delay is compared against
WATCHDOG_MAX_SKEW/2. If the delay exceeds the limit, we assume that
the system is just too busy. A warning will be printed to the console
and the clock skew check is skipped for this round.
Fixes: db3a34e174 ("clocksource: Retry clock read if long delays detected")
Fixes: 2e27e793e2 ("clocksource: Reduce clocksource-skew threshold")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a5bebc4f00 ]
Commit bfc6bb74e4 ("bpf: Implement verifier support for validation of async callbacks.")
added support for BPF_FUNC_timer_set_callback to
the __check_func_call() function. The test in __check_func_call() is
flaweed because it can mis-interpret a regular BPF-to-BPF pseudo-call
as a BPF_FUNC_timer_set_callback callback call.
Consider the conditional in the code:
if (insn->code == (BPF_JMP | BPF_CALL) &&
insn->imm == BPF_FUNC_timer_set_callback) {
The BPF_FUNC_timer_set_callback has value 170. This means that if you
have a BPF program that contains a pseudo-call with an instruction delta
of 170, this conditional will be found to be true by the verifier, and
it will interpret the pseudo-call as a callback. This leads to a mess
with the verification of the program because it makes the wrong
assumptions about the nature of this call.
Solution: include an explicit check to ensure that insn->src_reg == 0.
This ensures that calls cannot be mis-interpreted as an async callback
call.
Fixes: bfc6bb74e4 ("bpf: Implement verifier support for validation of async callbacks.")
Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220105210150.GH1559@oracle.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e60b0d12a9 ]
If we ever get to a point again where we convert a bogus looking <ptr>_or_null
typed register containing a non-zero fixed or variable offset, then lets not
reset these bounds to zero since they are not and also don't promote the register
to a <ptr> type, but instead leave it as <ptr>_or_null. Converting to a unknown
register could be an avenue as well, but then if we run into this case it would
allow to leak a kernel pointer this way.
Fixes: f1174f77b5 ("bpf/verifier: rework value tracking")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 81f6d49cce ]
Expedited RCU grace periods invoke sync_rcu_exp_select_node_cpus(), which
takes two passes over the leaf rcu_node structure's CPUs. The first
pass gathers up the current CPU and CPUs that are in dynticks idle mode.
The workqueue will report a quiescent state on their behalf later.
The second pass sends IPIs to the rest of the CPUs, but excludes the
current CPU, incorrectly assuming it has been included in the first
pass's list of CPUs.
Unfortunately the current CPU may have changed between the first and
second pass, due to the fact that the various rcu_node structures'
->lock fields have been dropped, thus momentarily enabling preemption.
This means that if the second pass's CPU was not on the first pass's
list, it will be ignored completely. There will be no IPI sent to
it, and there will be no reporting of quiescent states on its behalf.
Unfortunately, the expedited grace period will nevertheless be waiting
for that CPU to report a quiescent state, but with that CPU having no
reason to believe that such a report is needed.
The result will be an expedited grace period stall.
Fix this by no longer excluding the current CPU from consideration during
the second pass.
Fixes: b9ad4d6ed1 ("rcu: Avoid self-IPI in sync_rcu_exp_select_node_cpus()")
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 9b58e976b3 ]
When rt_runtime is modified from -1 to a valid control value, it may
cause the task to be throttled all the time. Operations like the following
will trigger the bug. E.g:
1. echo -1 > /proc/sys/kernel/sched_rt_runtime_us
2. Run a FIFO task named A that executes while(1)
3. echo 950000 > /proc/sys/kernel/sched_rt_runtime_us
When rt_runtime is -1, The rt period timer will not be activated when task
A enqueued. And then the task will be throttled after setting rt_runtime to
950,000. The task will always be throttled because the rt period timer is
not activated.
Fixes: d0b27fa778 ("sched: rt-group: synchonised bandwidth period")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Li Hua <hucool.lihua@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211203033618.11895-1-hucool.lihua@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit db52f57211 ]
Branch data available to BPF programs can be very useful to get stack traces
out of userspace application.
Commit fff7b64355 ("bpf: Add bpf_read_branch_records() helper") added BPF
support to capture branch records in x86. Enable this feature also for other
architectures as well by removing checks specific to x86.
If an architecture doesn't support branch records, bpf_read_branch_records()
still has appropriate checks and it will return an -EINVAL in that scenario.
Based on UAPI helper doc in include/uapi/linux/bpf.h, unsupported architectures
should return -ENOENT in such case. Hence, update the appropriate check to
return -ENOENT instead.
Selftest 'perf_branches' result on power9 machine which has the branch stacks
support:
- Before this patch:
[command]# ./test_progs -t perf_branches
#88/1 perf_branches/perf_branches_hw:FAIL
#88/2 perf_branches/perf_branches_no_hw:OK
#88 perf_branches:FAIL
Summary: 0/1 PASSED, 0 SKIPPED, 1 FAILED
- After this patch:
[command]# ./test_progs -t perf_branches
#88/1 perf_branches/perf_branches_hw:OK
#88/2 perf_branches/perf_branches_no_hw:OK
#88 perf_branches:OK
Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
Selftest 'perf_branches' result on power9 machine which doesn't have branch
stack report:
- After this patch:
[command]# ./test_progs -t perf_branches
#88/1 perf_branches/perf_branches_hw:SKIP
#88/2 perf_branches/perf_branches_no_hw:OK
#88 perf_branches:OK
Summary: 1/1 PASSED, 1 SKIPPED, 0 FAILED
Fixes: fff7b64355 ("bpf: Add bpf_read_branch_records() helper")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211206073315.77432-1-kjain@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 866de40744 ]
BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.
Fixes: 8580ac9404 ("bpf: Process in-kernel BTF")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211203053001.740945-1-houtao1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c5a2d43e99 ]
Make BTF log size limit to be the same as the verifier log size limit.
Otherwise tools that progressively increase log size and use the same log
for BTF loading and program loading will be hitting hard to debug EINVAL.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-7-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 014ba44e81 ]
select_idle_sibling() has a special case for tasks woken up by a per-CPU
kthread where the selected CPU is the previous one. For asymmetric CPU
capacity systems, the assumption was that the wakee couldn't have a
bigger utilization during task placement than it used to have during the
last activation. That was not considering uclamp.min which can completely
change between two task activations and as a consequence mandates the
fitness criterion asym_fits_capacity(), even for the exit path described
above.
Fixes: b4c9c9f156 ("sched/fair: Prefer prev cpu in asymmetric wakeup path")
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20211129173115.4006346-1-vincent.donnefort@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 8b4e74ccb5 ]
select_idle_sibling() has a special case for tasks woken up by a per-CPU
kthread, where the selected CPU is the previous one. However, the current
condition for this exit path is incomplete. A task can wake up from an
interrupt context (e.g. hrtimer), while a per-CPU kthread is running. A
such scenario would spuriously trigger the special case described above.
Also, a recent change made the idle task like a regular per-CPU kthread,
hence making that situation more likely to happen
(is_per_cpu_kthread(swapper) being true now).
Checking for task context makes sure select_idle_sibling() will not
interpret a wake up from any other context as a wake up by a per-CPU
kthread.
Fixes: 52262ee567 ("sched/fair: Allow a per-CPU kthread waking a task to stack on the same CPU, to fix XFS performance regression")
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20211201143450.479472-1-vincent.donnefort@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a674e48c54 upstream.
Currently three dma atomic pools are initialized as long as the relevant
kernel codes are built in. While in kdump kernel of x86_64, this is not
right when trying to create atomic_pool_dma, because there's no managed
pages in DMA zone. In the case, DMA zone only has low 1M memory
presented and locked down by memblock allocator. So no pages are added
into buddy of DMA zone. Please check commit f1d4d47c58 ("x86/setup:
Always reserve the first 1M of RAM").
Then in kdump kernel of x86_64, it always prints below failure message:
DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
swapper/0: page allocation failure: order:5, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-0.rc5.20210611git929d931f2b40.42.fc35.x86_64 #1
Hardware name: Dell Inc. PowerEdge R910/0P658H, BIOS 2.12.0 06/04/2018
Call Trace:
dump_stack+0x7f/0xa1
warn_alloc.cold+0x72/0xd6
__alloc_pages_slowpath.constprop.0+0xf29/0xf50
__alloc_pages+0x24d/0x2c0
alloc_page_interleave+0x13/0xb0
atomic_pool_expand+0x118/0x210
__dma_atomic_pool_init+0x45/0x93
dma_atomic_pool_init+0xdb/0x176
do_one_initcall+0x67/0x320
kernel_init_freeable+0x290/0x2dc
kernel_init+0xa/0x111
ret_from_fork+0x22/0x30
Mem-Info:
......
DMA: failed to allocate 128 KiB GFP_KERNEL|GFP_DMA pool for atomic allocation
DMA: preallocated 128 KiB GFP_KERNEL|GFP_DMA32 pool for atomic allocations
Here, let's check if DMA zone has managed pages, then create
atomic_pool_dma if yes. Otherwise just skip it.
Link: https://lkml.kernel.org/r/20211223094435.248523-3-bhe@redhat.com
Fixes: 6f599d8423 ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: David Rientjes <rientjes@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ff083a2d97 upstream.
Protect perf_guest_cbs with RCU to fix multiple possible errors. Luckily,
all paths that read perf_guest_cbs already require RCU protection, e.g. to
protect the callback chains, so only the direct perf_guest_cbs touchpoints
need to be modified.
Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure
perf_guest_cbs isn't reloaded between a !NULL check and a dereference.
Fixed via the READ_ONCE() in rcu_dereference().
Bug #2 is that on weakly-ordered architectures, updates to the callbacks
themselves are not guaranteed to be visible before the pointer is made
visible to readers. Fixed by the smp_store_release() in
rcu_assign_pointer() when the new pointer is non-NULL.
Bug #3 is that, because the callbacks are global, it's possible for
readers to run in parallel with an unregisters, and thus a module
implementing the callbacks can be unloaded while readers are in flight,
resulting in a use-after-free. Fixed by a synchronize_rcu() call when
unregistering callbacks.
Bug #1 escaped notice because it's extremely unlikely a compiler will
reload perf_guest_cbs in this sequence. perf_guest_cbs does get reloaded
for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest()
guard all but guarantees the consumer will win the race, e.g. to nullify
perf_guest_cbs, KVM has to completely exit the guest and teardown down
all VMs before KVM start its module unload / unregister sequence. This
also makes it all but impossible to encounter bug #3.
Bug #2 has not been a problem because all architectures that register
callbacks are strongly ordered and/or have a static set of callbacks.
But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping
perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming
kvm_intel module load/unload leads to:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:perf_misc_flags+0x1c/0x70
Call Trace:
perf_prepare_sample+0x53/0x6b0
perf_event_output_forward+0x67/0x160
__perf_event_overflow+0x52/0xf0
handle_pmi_common+0x207/0x300
intel_pmu_handle_irq+0xcf/0x410
perf_event_nmi_handler+0x28/0x50
nmi_handle+0xc7/0x260
default_do_nmi+0x6b/0x170
exc_nmi+0x103/0x130
asm_exc_nmi+0x76/0xbf
Fixes: 39447b386c ("perf: Enhance perf to allow for guest statistic collection from host")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-2-seanjc@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ no upstream commit given implicitly fixed through the larger refactoring
in c25b2ae136 ]
While auditing some other code, I noticed missing checks inside the pointer
arithmetic simulation, more specifically, adjust_ptr_min_max_vals(). Several
*_OR_NULL types are not rejected whereas they are _required_ to be rejected
given the expectation is that they get promoted into a 'real' pointer type
for the success case, that is, after an explicit != NULL check.
One case which stands out and is accessible from unprivileged (iff enabled
given disabled by default) is BPF ring buffer. From crafting a PoC, the NULL
check can be bypassed through an offset, and its id marking will then lead
to promotion of mem_or_null to a mem type.
bpf_ringbuf_reserve() helper can trigger this case through passing of reserved
flags, for example.
func#0 @0
0: R1=ctx(id=0,off=0,imm=0) R10=fp0
0: (7a) *(u64 *)(r10 -8) = 0
1: R1=ctx(id=0,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm
1: (18) r1 = 0x0
3: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm
3: (b7) r2 = 8
4: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R10=fp0 fp-8_w=mmmmmmmm
4: (b7) r3 = 0
5: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R3_w=invP0 R10=fp0 fp-8_w=mmmmmmmm
5: (85) call bpf_ringbuf_reserve#131
6: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
6: (bf) r6 = r0
7: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
7: (07) r0 += 1
8: R0_w=mem_or_null(id=2,ref_obj_id=2,off=1,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
8: (15) if r0 == 0x0 goto pc+4
R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
9: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
9: (62) *(u32 *)(r6 +0) = 0
R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
10: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
10: (bf) r1 = r6
11: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
11: (b7) r2 = 0
12: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R2_w=invP0 R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
12: (85) call bpf_ringbuf_submit#132
13: R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm
13: (b7) r0 = 0
14: R0_w=invP0 R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm
14: (95) exit
from 8 to 13: safe
processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0
OK
All three commits, that is b121b341e5 ("bpf: Add PTR_TO_BTF_ID_OR_NULL support"),
457f44363a ("bpf: Implement BPF ring buffer and verifier support for it"), and the
afbf21dce6 ("bpf: Support readonly/readwrite buffers in verifier") suffer the same
cause and their *_OR_NULL type pendants must be rejected in adjust_ptr_min_max_vals().
Make the test more robust by reusing reg_type_may_be_null() helper such that we catch
all *_OR_NULL types we have today and in future.
Note that pointer arithmetic on PTR_TO_BTF_ID, PTR_TO_RDONLY_BUF, and PTR_TO_RDWR_BUF
is generally allowed.
Fixes: b121b341e5 ("bpf: Add PTR_TO_BTF_ID_OR_NULL support")
Fixes: 457f44363a ("bpf: Implement BPF ring buffer and verifier support for it")
Fixes: afbf21dce6 ("bpf: Support readonly/readwrite buffers in verifier")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 07edfece8b upstream.
At CPU-hotplug time, unbind_worker() may preempt a worker while it is
waking up. In that case the following scenario can happen:
unbind_workers() wq_worker_running()
-------------- -------------------
if (!(worker->flags & WORKER_NOT_RUNNING))
//PREEMPTED by unbind_workers
worker->flags |= WORKER_UNBOUND;
[...]
atomic_set(&pool->nr_running, 0);
//resume to worker
atomic_inc(&worker->pool->nr_running);
After unbind_worker() resets pool->nr_running, the value is expected to
remain 0 until the pool ever gets rebound in case cpu_up() is called on
the target CPU in the future. But here the race leaves pool->nr_running
with a value of 1, triggering the following warning when the worker goes
idle:
WARNING: CPU: 3 PID: 34 at kernel/workqueue.c:1823 worker_enter_idle+0x95/0xc0
Modules linked in:
CPU: 3 PID: 34 Comm: kworker/3:0 Not tainted 5.16.0-rc1+ #34
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
Workqueue: 0x0 (rcu_par_gp)
RIP: 0010:worker_enter_idle+0x95/0xc0
Code: 04 85 f8 ff ff ff 39 c1 7f 09 48 8b 43 50 48 85 c0 74 1b 83 e2 04 75 99 8b 43 34 39 43 30 75 91 8b 83 00 03 00 00 85 c0 74 87 <0f> 0b 5b c3 48 8b 35 70 f1 37 01 48 8d 7b 48 48 81 c6 e0 93 0
RSP: 0000:ffff9b7680277ed0 EFLAGS: 00010086
RAX: 00000000ffffffff RBX: ffff93465eae9c00 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff9346418a0000 RDI: ffff934641057140
RBP: ffff934641057170 R08: 0000000000000001 R09: ffff9346418a0080
R10: ffff9b768027fdf0 R11: 0000000000002400 R12: ffff93465eae9c20
R13: ffff93465eae9c20 R14: ffff93465eae9c70 R15: ffff934641057140
FS: 0000000000000000(0000) GS:ffff93465eac0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001cc0c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
worker_thread+0x89/0x3d0
? process_one_work+0x400/0x400
kthread+0x162/0x190
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
</TASK>
Also due to this incorrect "nr_running == 1", further queued work may
end up not being served, because no worker is awaken at work insert time.
This raises rcutorture writer stalls for example.
Fix this with disabling preemption in the right place in
wq_worker_running().
It's worth noting that if the worker migrates and runs concurrently with
unbind_workers(), it is guaranteed to see the WORKER_UNBOUND flag update
due to set_cpus_allowed_ptr() acquiring/releasing rq->lock.
Fixes: 6d25be5782 ("sched/core, workqueues: Distangle worker accounting from rq lock")
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e574576416 upstream.
cgroup process migration permission checks are performed at write time as
whether a given operation is allowed or not is dependent on the content of
the write - the PID. This currently uses current's cgroup namespace which is
a potential security weakness as it may allow scenarios where a less
privileged process tricks a more privileged one into writing into a fd that
it created.
This patch makes cgroup remember the cgroup namespace at the time of open
and uses it for migration permission checks instad of current's. Note that
this only applies to cgroup2 as cgroup1 doesn't have namespace support.
This also fixes a use-after-free bug on cgroupns reported in
https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com
Note that backporting this fix also requires the preceding patch.
Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Reported-by: syzbot+50f5cf33a284ce738b62@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com
Fixes: 5136f6365c ("cgroup: implement "nsdelegate" mount option")
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0d2b5955b3 upstream.
of->priv is currently used by each interface file implementation to store
private information. This patch collects the current two private data usages
into struct cgroup_file_ctx which is allocated and freed by the common path.
This allows generic private data which applies to multiple files, which will
be used to in the following patch.
Note that cgroup_procs iterator is now embedded as procs.iter in the new
cgroup_file_ctx so that it doesn't need to be allocated and freed
separately.
v2: union dropped from cgroup_file_ctx and the procs iterator is embedded in
cgroup_file_ctx as suggested by Linus.
v3: Michal pointed out that cgroup1's procs pidlist uses of->priv too.
Converted. Didn't change to embedded allocation as cgroup1 pidlists get
stored for caching.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1756d7994a upstream.
cgroup process migration permission checks are performed at write time as
whether a given operation is allowed or not is dependent on the content of
the write - the PID. This currently uses current's credentials which is a
potential security weakness as it may allow scenarios where a less
privileged process tricks a more privileged one into writing into a fd that
it created.
This patch makes both cgroup2 and cgroup1 process migration interfaces to
use the credentials saved at the time of open (file->f_cred) instead of
current's.
Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Fixes: 187fe84067 ("cgroup: require write perm on common ancestor when moving processes on the default hierarchy")
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 823e670f7e upstream.
With the new osnoise tracer, we are seeing the below splat:
Kernel attempted to read user page (c7d880000) - exploit attempt? (uid: 0)
BUG: Unable to handle kernel data access on read at 0xc7d880000
Faulting instruction address: 0xc0000000002ffa10
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
...
NIP [c0000000002ffa10] __trace_array_vprintk.part.0+0x70/0x2f0
LR [c0000000002ff9fc] __trace_array_vprintk.part.0+0x5c/0x2f0
Call Trace:
[c0000008bdd73b80] [c0000000001c49cc] put_prev_task_fair+0x3c/0x60 (unreliable)
[c0000008bdd73be0] [c000000000301430] trace_array_printk_buf+0x70/0x90
[c0000008bdd73c00] [c0000000003178b0] trace_sched_switch_callback+0x250/0x290
[c0000008bdd73c90] [c000000000e70d60] __schedule+0x410/0x710
[c0000008bdd73d40] [c000000000e710c0] schedule+0x60/0x130
[c0000008bdd73d70] [c000000000030614] interrupt_exit_user_prepare_main+0x264/0x270
[c0000008bdd73de0] [c000000000030a70] syscall_exit_prepare+0x150/0x180
[c0000008bdd73e10] [c00000000000c174] system_call_vectored_common+0xf4/0x278
osnoise tracer on ppc64le is triggering osnoise_taint() for negative
duration in get_int_safe_duration() called from
trace_sched_switch_callback()->thread_exit().
The problem though is that the check for a valid trace_percpu_buffer is
incorrect in get_trace_buf(). The check is being done after calculating
the pointer for the current cpu, rather than on the main percpu pointer.
Fix the check to be against trace_percpu_buffer.
Link: https://lkml.kernel.org/r/a920e4272e0b0635cf20c444707cbce1b2c8973d.1640255304.git.naveen.n.rao@linux.vnet.ibm.com
Cc: stable@vger.kernel.org
Fixes: e2ace00117 ("tracing: Choose static tp_printk buffer by explicit nesting count")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 71d2bcec2d ]
When booting with crashkernel= on the kernel command line a warning
similar to
Kernel command line: ro console=ttyS0 crashkernel=256M
Unknown kernel command line parameters "crashkernel=256M", will be passed to user space.
is printed.
This comes from crashkernel= being parsed independent from the kernel
parameter handling mechanism. So the code in init/main.c doesn't know
that crashkernel= is a valid kernel parameter and prints this incorrect
warning.
Suppress the warning by adding a dummy early_param handler for
crashkernel=.
Link: https://lkml.kernel.org/r/20211208133443.6867-1-prudo@redhat.com
Fixes: 86d1919a4f ("init: print out unknown kernel parameters")
Signed-off-by: Philipp Rudo <prudo@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 59ec71575a ]
The semantics of the rlimit max values differs from ucounts itself. When
creating a new userns, we store the current rlimit of the process in
ucount_max. Thus, the value of the limit in the parent userns is saved
in the created one.
The problem is that now we are taking the maximum value for counter from
the same userns. So for init_user_ns it will always be RLIM_INFINITY.
To fix the problem we need to check the counter value with the max value
stored in userns.
Reproducer:
su - test -c "ulimit -u 3; sleep 5 & sleep 6 & unshare -U --map-root-user sh -c 'sleep 7 & sleep 8 & date; wait'"
Before:
[1] 175
[2] 176
Fri Nov 26 13:48:20 UTC 2021
[1]- Done sleep 5
[2]+ Done sleep 6
After:
[1] 167
[2] 168
sh: fork: retry: Resource temporarily unavailable
sh: fork: retry: Resource temporarily unavailable
sh: fork: retry: Resource temporarily unavailable
sh: fork: retry: Resource temporarily unavailable
sh: fork: retry: Resource temporarily unavailable
sh: fork: retry: Resource temporarily unavailable
sh: fork: retry: Resource temporarily unavailable
sh: fork: Interrupted system call
[1]- Done sleep 5
[2]+ Done sleep 6
Fixes: c54b245d01 ("Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace")
Reported-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/024ec805f6e16896f0b23e094773790d171d2c1c.1638218242.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 2431774f04 upstream.
This commit marks accesses to the rcu_state.n_force_qs. These data
races are hard to make happen, but syzkaller was equal to the task.
Reported-by: syzbot+e08a83a1940ec3846cd5@syzkaller.appspotmail.com
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8f556a326c upstream.
Optimistic spinning needs to be terminated when the spinning waiter is not
longer the top waiter on the lock, but the condition is negated. It
terminates if the waiter is the top waiter, which is defeating the whole
purpose.
Fixes: c3123c4314 ("locking/rtmutex: Dont dereference waiter lockless")
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211217074207.77425-1-qiang1.zhang@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4e8c11b6b3 upstream.
Even after commit e1d7ba8735 ("time: Always make sure wall_to_monotonic
isn't positive") it is still possible to make wall_to_monotonic positive
by running the following code:
int main(void)
{
struct timespec time;
clock_gettime(CLOCK_MONOTONIC, &time);
time.tv_nsec = 0;
clock_settime(CLOCK_REALTIME, &time);
return 0;
}
The reason is that the second parameter of timespec64_compare(), ts_delta,
may be unnormalized because the delta is calculated with an open coded
substraction which causes the comparison of tv_sec to yield the wrong
result:
wall_to_monotonic = { .tv_sec = -10, .tv_nsec = 900000000 }
ts_delta = { .tv_sec = -9, .tv_nsec = -900000000 }
That makes timespec64_compare() claim that wall_to_monotonic < ts_delta,
but actually the result should be wall_to_monotonic > ts_delta.
After normalization, the result of timespec64_compare() is correct because
the tv_sec comparison is not longer misleading:
wall_to_monotonic = { .tv_sec = -10, .tv_nsec = 900000000 }
ts_delta = { .tv_sec = -10, .tv_nsec = 100000000 }
Use timespec64_sub() to ensure that ts_delta is normalized, which fixes the
issue.
Fixes: e1d7ba8735 ("time: Always make sure wall_to_monotonic isn't positive")
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211213135727.1656662-1-liaoyu15@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f4b3ee3c85 upstream.
If the audit daemon were ever to get stuck in a stopped state the
kernel's kauditd_thread() could get blocked attempting to send audit
records to the userspace audit daemon. With the kernel thread
blocked it is possible that the audit queue could grow unbounded as
certain audit record generating events must be exempt from the queue
limits else the system enter a deadlock state.
This patch resolves this problem by lowering the kernel thread's
socket sending timeout from MAX_SCHEDULE_TIMEOUT to HZ/10 and tweaks
the kauditd_send_queue() function to better manage the various audit
queues when connection problems occur between the kernel and the
audit daemon. With this patch, the backlog may temporarily grow
beyond the defined limits when the audit daemon is stopped and the
system is under heavy audit pressure, but kauditd_thread() will
continue to make progress and drain the queues as it would for other
connection problems. For example, with the audit daemon put into a
stopped state and the system configured to audit every syscall it
was still possible to shutdown the system without a kernel panic,
deadlock, etc.; granted, the system was slow to shutdown but that is
to be expected given the extreme pressure of recording every syscall.
The timeout value of HZ/10 was chosen primarily through
experimentation and this developer's "gut feeling". There is likely
no one perfect value, but as this scenario is limited in scope (root
privileges would be needed to send SIGSTOP to the audit daemon), it
is likely not worth exposing this as a tunable at present. This can
always be done at a later date if it proves necessary.
Cc: stable@vger.kernel.org
Fixes: 5b52330bbf ("audit: fix auditd/kernel connection state tracking")
Reported-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Tested-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit a82fe085f3 upstream.
The implementation of BPF_CMPXCHG on a high level has the following parameters:
.-[old-val] .-[new-val]
BPF_R0 = cmpxchg{32,64}(DST_REG + insn->off, BPF_R0, SRC_REG)
`-[mem-loc] `-[old-val]
Given a BPF insn can only have two registers (dst, src), the R0 is fixed and
used as an auxilliary register for input (old value) as well as output (returning
old value from memory location). While the verifier performs a number of safety
checks, it misses to reject unprivileged programs where R0 contains a pointer as
old value.
Through brute-forcing it takes about ~16sec on my machine to leak a kernel pointer
with BPF_CMPXCHG. The PoC is basically probing for kernel addresses by storing the
guessed address into the map slot as a scalar, and using the map value pointer as
R0 while SRC_REG has a canary value to detect a matching address.
Fix it by checking R0 for pointers, and reject if that's the case for unprivileged
programs.
Fixes: 5ffa25502b ("bpf: Add instructions for atomic_[cmp]xchg")
Reported-by: Ryota Shiga (Flatt Security)
Acked-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e572ff80f0 upstream.
Make the bounds propagation in __reg_assign_32_into_64() slightly more
robust and readable by aligning it similarly as we did back in the
__reg_combine_64_into_32() counterpart. Meaning, only propagate or
pessimize them as a smin/smax pair.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3cf2b61eb0 upstream.
For the case where both s32_{min,max}_value bounds are positive, the
__reg_assign_32_into_64() directly propagates them to their 64 bit
counterparts, otherwise it pessimises them into [0,u32_max] universe and
tries to refine them later on by learning through the tnum as per comment
in mentioned function. However, that does not always happen, for example,
in mov32 operation we call zext_32_to_64(dst_reg) which invokes the
__reg_assign_32_into_64() as is without subsequent bounds update as
elsewhere thus no refinement based on tnum takes place.
Thus, not calling into the __update_reg_bounds() / __reg_deduce_bounds() /
__reg_bound_offset() triplet as we do, for example, in case of ALU ops via
adjust_scalar_min_max_vals(), will lead to more pessimistic bounds when
dumping the full register state:
Before fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=0,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Technically, the smin_value=0 and smax_value=4294967295 bounds are not
incorrect, but given the register is still a constant, they break assumptions
about const scalars that smin_value == smax_value and umin_value == umax_value.
After fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Without the smin_value == smax_value and umin_value == umax_value invariant
being intact for const scalars, it is possible to leak out kernel pointers
from unprivileged user space if the latter is enabled. For example, when such
registers are involved in pointer arithmtics, then adjust_ptr_min_max_vals()
will taint the destination register into an unknown scalar, and the latter
can be exported and stored e.g. into a BPF map value.
Fixes: 3f50f132d8 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Kuee K1r0a <liulin063@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 7d3baf0afa upstream.
The change in commit 37086bfdc7 ("bpf: Propagate stack bounds to registers
in atomics w/ BPF_FETCH") around check_mem_access() handling is buggy since
this would allow for unprivileged users to leak kernel pointers. For example,
an atomic fetch/and with -1 on a stack destination which holds a spilled
pointer will migrate the spilled register type into a scalar, which can then
be exported out of the program (since scalar != pointer) by dumping it into
a map value.
The original implementation of XADD was preventing this situation by using
a double call to check_mem_access() one with BPF_READ and a subsequent one
with BPF_WRITE, in both cases passing -1 as a placeholder value instead of
register as per XADD semantics since it didn't contain a value fetch. The
BPF_READ also included a check in check_stack_read_fixed_off() which rejects
the program if the stack slot is of __is_pointer_value() if dst_regno < 0.
The latter is to distinguish whether we're dealing with a regular stack spill/
fill or some arithmetical operation which is disallowed on non-scalars, see
also 6e7e63cbb0 ("bpf: Forbid XADD on spilled pointers for unprivileged
users") for more context on check_mem_access() and its handling of placeholder
value -1.
One minimally intrusive option to fix the leak is for the BPF_FETCH case to
initially check the BPF_READ case via check_mem_access() with -1 as register,
followed by the actual load case with non-negative load_reg to propagate
stack bounds to registers.
Fixes: 37086bfdc7 ("bpf: Propagate stack bounds to registers in atomics w/ BPF_FETCH")
Reported-by: <n4ke4mry@gmail.com>
Acked-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 42288cb44c upstream.
Several ->poll() implementations are special in that they use a
waitqueue whose lifetime is the current task, rather than the struct
file as is normally the case. This is okay for blocking polls, since a
blocking poll occurs within one task; however, non-blocking polls
require another solution. This solution is for the queue to be cleared
before it is freed, using 'wake_up_poll(wq, EPOLLHUP | POLLFREE);'.
However, that has a bug: wake_up_poll() calls __wake_up() with
nr_exclusive=1. Therefore, if there are multiple "exclusive" waiters,
and the wakeup function for the first one returns a positive value, only
that one will be called. That's *not* what's needed for POLLFREE;
POLLFREE is special in that it really needs to wake up everyone.
Considering the three non-blocking poll systems:
- io_uring poll doesn't handle POLLFREE at all, so it is broken anyway.
- aio poll is unaffected, since it doesn't support exclusive waits.
However, that's fragile, as someone could add this feature later.
- epoll doesn't appear to be broken by this, since its wakeup function
returns 0 when it sees POLLFREE. But this is fragile.
Although there is a workaround (see epoll), it's better to define a
function which always sends POLLFREE to all waiters. Add such a
function. Also make it verify that the queue really becomes empty after
all waiters have been woken up.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211209010455.42744-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e4779015fd upstream.
Patch series "mm/damon: Fix fake /proc/loadavg reports", v3.
This patchset fixes DAMON's fake load report issue. The first patch
makes yet another variant of usleep_range() for this fix, and the second
patch fixes the issue of DAMON by making it using the newly introduced
function.
This patch (of 2):
Some kernel threads such as DAMON could need to repeatedly sleep in
micro seconds level. Because usleep_range() sleeps in uninterruptible
state, however, such threads would make /proc/loadavg reports fake load.
To help such cases, this commit implements a variant of usleep_range()
called usleep_idle_range(). It is same to usleep_range() but sets the
state of the current task as TASK_IDLE while sleeping.
Link: https://lkml.kernel.org/r/20211126145015.15862-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20211126145015.15862-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 2fa7d94afc upstream.
The first commit cited below attempts to fix the off-by-one error that
appeared in some comparisons with an open range. Due to this error,
arithmetically equivalent pieces of code could get different verdicts
from the verifier, for example (pseudocode):
// 1. Passes the verifier:
if (data + 8 > data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
// 2. Rejected by the verifier (should still pass):
if (data + 7 >= data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
The attempted fix, however, shifts the range by one in a wrong
direction, so the bug not only remains, but also such piece of code
starts failing in the verifier:
// 3. Rejected by the verifier, but the check is stricter than in #1.
if (data + 8 >= data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
The change performed by that fix converted an off-by-one bug into
off-by-two. The second commit cited below added the BPF selftests
written to ensure than code chunks like #3 are rejected, however,
they should be accepted.
This commit fixes the off-by-two error by adjusting new_range in the
right direction and fixes the tests by changing the range into the
one that should actually fail.
Fixes: fb2a311a31 ("bpf: fix off by one for range markings with L{T, E} patterns")
Fixes: b37242c773 ("bpf: add test cases to bpf selftests to cover all access tests")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211130181607.593149-1-maximmi@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 315c4f8848 ]
Commit d81ae8aac8 ("sched/uclamp: Fix initialization of struct
uclamp_rq") introduced a bug where uclamp_max of the rq is not reset to
match the woken up task's uclamp_max when the rq is idle.
The code was relying on rq->uclamp_max initialized to zero, so on first
enqueue
static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p,
enum uclamp_id clamp_id)
{
...
if (uc_se->value > READ_ONCE(uc_rq->value))
WRITE_ONCE(uc_rq->value, uc_se->value);
}
was actually resetting it. But since commit d81ae8aac8 changed the
default to 1024, this no longer works. And since rq->uclamp_flags is
also initialized to 0, neither above code path nor uclamp_idle_reset()
update the rq->uclamp_max on first wake up from idle.
This is only visible from first wake up(s) until the first dequeue to
idle after enabling the static key. And it only matters if the
uclamp_max of this task is < 1024 since only then its uclamp_max will be
effectively ignored.
Fix it by properly initializing rq->uclamp_flags = UCLAMP_FLAG_IDLE to
ensure uclamp_idle_reset() is called which then will update the rq
uclamp_max value as expected.
Fixes: d81ae8aac8 ("sched/uclamp: Fix initialization of struct uclamp_rq")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20211202112033.1705279-1-qais.yousef@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 9ed20bafc8 ]
__setup() callbacks expect 1 for success and 0 for failure. Correct the
usage here to reflect that.
Fixes: 826bfeb37b ("preempt/dynamic: Support dynamic preempt with preempt= boot option")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211203233203.133581-1-ahalaney@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 450fec13d9 upstream.
When comparing two strings for the "onmatch" histogram trigger, fields
that are strings use string comparisons, which do not care about being
signed or not.
Do not fail to match two string fields if one is unsigned char array and
the other is a signed char array.
Link: https://lore.kernel.org/all/20211129123043.5cfd687a@gandalf.local.home/
Cc: stable@vgerk.kernel.org
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Yafang Shao <laoar.shao@gmail.com>
Fixes: b05e89ae7c ("tracing: Accept different type for synthetic event fields")
Reviewed-by: Masami Hiramatsu <mhiramatsu@kernel.org>
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6bbfa44116 upstream.
The 'kprobe::data_size' is unsigned, thus it can not be negative. But if
user sets it enough big number (e.g. (size_t)-8), the result of 'data_size
+ sizeof(struct kretprobe_instance)' becomes smaller than sizeof(struct
kretprobe_instance) or zero. In result, the kretprobe_instance are
allocated without enough memory, and kretprobe accesses outside of
allocated memory.
To avoid this issue, introduce a max limitation of the
kretprobe::data_size. 4KB per instance should be OK.
Link: https://lkml.kernel.org/r/163836995040.432120.10322772773821182925.stgit@devnote2
Cc: stable@vger.kernel.org
Fixes: f47cd9b553 ("kprobes: kretprobe user entry-handler")
Reported-by: zhangyue <zhangyue1@kylinos.cn>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 2ef75e9bd2 ]
If trace_seq becomes full, trace_seq_vprintf() no longer consumes
arguments from va_list, making va_list out of sync with format
processing by trace_check_vprintf().
This causes va_arg() in trace_check_vprintf() to return wrong
positional argument, which results into a WARN_ON_ONCE() hit.
ftrace_stress_test from LTP triggers this situation.
Fix it by explicitly avoiding further use if va_list at the point
when it's consistency can no longer be guaranteed.
Link: https://lkml.kernel.org/r/20211118145516.13219-1-nikita.yushchenko@virtuozzo.com
Signed-off-by: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 6cb206508b upstream.
When pid filtering is activated in an instance, all of the events trace
files for that instance has the PID_FILTER flag set. This determines
whether or not pid filtering needs to be done on the event, otherwise the
event is executed as normal.
If pid filtering is enabled when an event is created (via a dynamic event
or modules), its flag is not updated to reflect the current state, and the
events are not filtered properly.
Cc: stable@vger.kernel.org
Fixes: 3fdaf80f4a ("tracing: Implement event pid filtering")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit dce1ca0525 ]
To hot unplug a CPU, the idle task on that CPU calls a few layers of C
code before finally leaving the kernel. When KASAN is in use, poisoned
shadow is left around for each of the active stack frames, and when
shadow call stacks are in use. When shadow call stacks (SCS) are in use
the task's saved SCS SP is left pointing at an arbitrary point within
the task's shadow call stack.
When a CPU is offlined than onlined back into the kernel, this stale
state can adversely affect execution. Stale KASAN shadow can alias new
stackframes and result in bogus KASAN warnings. A stale SCS SP is
effectively a memory leak, and prevents a portion of the shadow call
stack being used. Across a number of hotplug cycles the idle task's
entire shadow call stack can become unusable.
We previously fixed the KASAN issue in commit:
e1b77c9298 ("sched/kasan: remove stale KASAN poison after hotplug")
... by removing any stale KASAN stack poison immediately prior to
onlining a CPU.
Subsequently in commit:
f1a0a376ca ("sched/core: Initialize the idle task with preemption disabled")
... the refactoring left the KASAN and SCS cleanup in one-time idle
thread initialization code rather than something invoked prior to each
CPU being onlined, breaking both as above.
We fixed SCS (but not KASAN) in commit:
63acd42c0d ("sched/scs: Reset the shadow stack when idle_task_exit")
... but as this runs in the context of the idle task being offlined it's
potentially fragile.
To fix these consistently and more robustly, reset the SCS SP and KASAN
shadow of a CPU's idle task immediately before we online that CPU in
bringup_cpu(). This ensures the idle task always has a consistent state
when it is running, and removes the need to so so when exiting an idle
task.
Whenever any thread is created, dup_task_struct() will give the task a
stack which is free of KASAN shadow, and initialize the task's SCS SP,
so there's no need to specially initialize either for idle thread within
init_idle(), as this was only necessary to handle hotplug cycles.
I've tested this on arm64 with:
* gcc 11.1.0, defconfig +KASAN_INLINE, KASAN_STACK
* clang 12.0.0, defconfig +KASAN_INLINE, KASAN_STACK, SHADOW_CALL_STACK
... offlining and onlining CPUS with:
| while true; do
| for C in /sys/devices/system/cpu/cpu*/online; do
| echo 0 > $C;
| echo 1 > $C;
| done
| done
Fixes: f1a0a376ca ("sched/core: Initialize the idle task with preemption disabled")
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
Link: https://lore.kernel.org/lkml/20211115113310.35693-1-mark.rutland@arm.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 73743c3b09 ]
syzbot reported that the warning in perf_sigtrap() fires, saying that
the event's task does not match current:
| WARNING: CPU: 0 PID: 9090 at kernel/events/core.c:6446 perf_pending_event+0x40d/0x4b0 kernel/events/core.c:6513
| Modules linked in:
| CPU: 0 PID: 9090 Comm: syz-executor.1 Not tainted 5.15.0-syzkaller #0
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
| RIP: 0010:perf_sigtrap kernel/events/core.c:6446 [inline]
| RIP: 0010:perf_pending_event_disable kernel/events/core.c:6470 [inline]
| RIP: 0010:perf_pending_event+0x40d/0x4b0 kernel/events/core.c:6513
| ...
| Call Trace:
| <IRQ>
| irq_work_single+0x106/0x220 kernel/irq_work.c:211
| irq_work_run_list+0x6a/0x90 kernel/irq_work.c:242
| irq_work_run+0x4f/0xd0 kernel/irq_work.c:251
| __sysvec_irq_work+0x95/0x3d0 arch/x86/kernel/irq_work.c:22
| sysvec_irq_work+0x8e/0xc0 arch/x86/kernel/irq_work.c:17
| </IRQ>
| <TASK>
| asm_sysvec_irq_work+0x12/0x20 arch/x86/include/asm/idtentry.h:664
| RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
| RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:194
| ...
| coredump_task_exit kernel/exit.c:371 [inline]
| do_exit+0x1865/0x25c0 kernel/exit.c:771
| do_group_exit+0xe7/0x290 kernel/exit.c:929
| get_signal+0x3b0/0x1ce0 kernel/signal.c:2820
| arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
| handle_signal_work kernel/entry/common.c:148 [inline]
| exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
| exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
| __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
| syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
| do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
| entry_SYSCALL_64_after_hwframe+0x44/0xae
On x86 this shouldn't happen, which has arch_irq_work_raise().
The test program sets up a perf event with sigtrap set to fire on the
'sched_wakeup' tracepoint, which fired in ttwu_do_wakeup().
This happened because the 'sched_wakeup' tracepoint also takes a task
argument passed on to perf_tp_event(), which is used to deliver the
event to that other task.
Since we cannot deliver synchronous signals to other tasks, skip an event if
perf_tp_event() is targeted at another task and perf_event_attr::sigtrap is
set, which will avoid ever entering perf_sigtrap() for such events.
Fixes: 97ba62b278 ("perf: Add support for SIGTRAP on perf events")
Reported-by: syzbot+663359e32ce6f1a305ad@syzkaller.appspotmail.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YYpoCOBmC/kJWfmI@elver.google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d257cc8cb8 ]
There are some inconsistency in the way that the handoff bit is being
handled in readers and writers that lead to a race condition.
Firstly, when a queue head writer set the handoff bit, it will clear
it when the writer is being killed or interrupted on its way out
without acquiring the lock. That is not the case for a queue head
reader. The handoff bit will simply be inherited by the next waiter.
Secondly, in the out_nolock path of rwsem_down_read_slowpath(), both
the waiter and handoff bits are cleared if the wait queue becomes
empty. For rwsem_down_write_slowpath(), however, the handoff bit is
not checked and cleared if the wait queue is empty. This can
potentially make the handoff bit set with empty wait queue.
Worse, the situation in rwsem_down_write_slowpath() relies on wstate,
a variable set outside of the critical section containing the ->count
manipulation, this leads to race condition where RWSEM_FLAG_HANDOFF
can be double subtracted, corrupting ->count.
To make the handoff bit handling more consistent and robust, extract
out handoff bit clearing code into the new rwsem_del_waiter() helper
function. Also, completely eradicate wstate; always evaluate
everything inside the same critical section.
The common function will only use atomic_long_andnot() to clear bits
when the wait queue is empty to avoid possible race condition. If the
first waiter with handoff bit set is killed or interrupted to exit the
slowpath without acquiring the lock, the next waiter will inherit the
handoff bit.
While at it, simplify the trylock for loop in
rwsem_down_write_slowpath() to make it easier to read.
Fixes: 4f23dbc1e6 ("locking/rwsem: Implement lock handoff to prevent lock starvation")
Reported-by: Zhenhua Ma <mazhenhua@xiaomi.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211116012912.723980-1-longman@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cefcf24b4d ]
Commit 39fbef4b0f ("PM: hibernate: Get block device exclusively in
swsusp_check()") changed the opening mode of the block device to
(FMODE_READ | FMODE_EXCL).
In the corresponding calls to swsusp_close(), the mode is still just
FMODE_READ which triggers the warning in blkdev_flush_mapping() on
resume from hibernate.
So, use the mode (FMODE_READ | FMODE_EXCL) also when closing the
device.
Fixes: 39fbef4b0f ("PM: hibernate: Get block device exclusively in swsusp_check()")
Signed-off-by: Thomas Zeitlhofer <thomas.zeitlhofer+lkml@ze-it.at>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a55f224ff5 upstream.
If a event is filtered by pid and a trigger that requires processing of
the event to happen is a attached to the event, the discard portion does
not take the pid filtering into account, and the event will then be
recorded when it should not have been.
Cc: stable@vger.kernel.org
Fixes: 3fdaf80f4a ("tracing: Implement event pid filtering")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit fcb116bc43 upstream.
Recently to prevent issues with SECCOMP_RET_KILL and similar signals
being changed before they are delivered SA_IMMUTABLE was added.
Unfortunately this broke debuggers[1][2] which reasonably expect
to be able to trap synchronous SIGTRAP and SIGSEGV even when
the target process is not configured to handle those signals.
Add force_exit_sig and use it instead of force_fatal_sig where
historically the code has directly called do_exit. This has the
implementation benefits of going through the signal exit path
(including generating core dumps) without the danger of allowing
userspace to ignore or change these signals.
This avoids userspace regressions as older kernels exited with do_exit
which debuggers also can not intercept.
In the future is should be possible to improve the quality of
implementation of the kernel by changing some of these force_exit_sig
calls to force_fatal_sig. That can be done where it matters on
a case-by-case basis with careful analysis.
Reported-by: Kyle Huey <me@kylehuey.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
[1] https://lkml.kernel.org/r/CAP045AoMY4xf8aC_4QU_-j7obuEPYgTcnQQP3Yxk=2X90jtpjw@mail.gmail.com
[2] https://lkml.kernel.org/r/20211117150258.GB5403@xsang-OptiPlex-9020
Fixes: 00b06da29c ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed")
Fixes: a3616a3c02 ("signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die")
Fixes: 83a1f27ad7 ("signal/powerpc: On swapcontext failure force SIGSEGV")
Fixes: 9bc508cf07 ("signal/s390: Use force_sigsegv in default_trap_handler")
Fixes: 086ec444f8 ("signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig")
Fixes: c317d306d5 ("signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails")
Fixes: 695dd0d634 ("signal/x86: In emulate_vsyscall force a signal instead of calling do_exit")
Fixes: 1fbd60df8a ("signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.")
Fixes: 941edc5bf1 ("exit/syscall_user_dispatch: Send ordinary signals on failure")
Link: https://lkml.kernel.org/r/871r3dqfv8.fsf_-_@email.froward.int.ebiederm.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Thomas Backlund <tmb@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e349d945fa upstream.
Recently to prevent issues with SECCOMP_RET_KILL and similar signals
being changed before they are delivered SA_IMMUTABLE was added.
Unfortunately this broke debuggers[1][2] which reasonably expect to be
able to trap synchronous SIGTRAP and SIGSEGV even when the target
process is not configured to handle those signals.
Update force_sig_to_task to support both the case when we can allow
the debugger to intercept and possibly ignore the signal and the case
when it is not safe to let userspace know about the signal until the
process has exited.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Kyle Huey <me@kylehuey.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Cc: stable@vger.kernel.org
[1] https://lkml.kernel.org/r/CAP045AoMY4xf8aC_4QU_-j7obuEPYgTcnQQP3Yxk=2X90jtpjw@mail.gmail.com
[2] https://lkml.kernel.org/r/20211117150258.GB5403@xsang-OptiPlex-9020
Fixes: 00b06da29c ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed")
Link: https://lkml.kernel.org/r/877dd5qfw5.fsf_-_@email.froward.int.ebiederm.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Thomas Backlund <tmb@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 941edc5bf1 upstream.
Use force_fatal_sig instead of calling do_exit directly. This ensures
the ordinary signal handling path gets invoked, core dumps as
appropriate get created, and for multi-threaded processes all of the
threads are terminated not just a single thread.
When asked Gabriel Krisman Bertazi <krisman@collabora.com> said [1]:
> ebiederm@xmission.com (Eric W. Biederman) asked:
>
> > Why does do_syscal_user_dispatch call do_exit(SIGSEGV) and
> > do_exit(SIGSYS) instead of force_sig(SIGSEGV) and force_sig(SIGSYS)?
> >
> > Looking at the code these cases are not expected to happen, so I would
> > be surprised if userspace depends on any particular behaviour on the
> > failure path so I think we can change this.
>
> Hi Eric,
>
> There is not really a good reason, and the use case that originated the
> feature doesn't rely on it.
>
> Unless I'm missing yet another problem and others correct me, I think
> it makes sense to change it as you described.
>
> > Is using do_exit in this way something you copied from seccomp?
>
> I'm not sure, its been a while, but I think it might be just that. The
> first prototype of SUD was implemented as a seccomp mode.
If at some point it becomes interesting we could relax
"force_fatal_sig(SIGSEGV)" to instead say
"force_sig_fault(SIGSEGV, SEGV_MAPERR, sd->selector)".
I avoid doing that in this patch to avoid making it possible
to catch currently uncatchable signals.
Cc: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
[1] https://lkml.kernel.org/r/87mtr6gdvi.fsf@collabora.com
Link: https://lkml.kernel.org/r/20211020174406.17889-14-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Thomas Backlund <tmb@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
