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Kuniyuki Iwashima a31a647a3d seccomp: Move copy_seccomp() to no failure path. 
[ Upstream commit a1140cb215 ]

Our syzbot instance reported memory leaks in do_seccomp() [0], similar
to the report [1].  It shows that we miss freeing struct seccomp_filter
and some objects included in it.

We can reproduce the issue with the program below [2] which calls one
seccomp() and two clone() syscalls.

The first clone()d child exits earlier than its parent and sends a
signal to kill it during the second clone(), more precisely before the
fatal_signal_pending() test in copy_process().  When the parent receives
the signal, it has to destroy the embryonic process and return -EINTR to
user space.  In the failure path, we have to call seccomp_filter_release()
to decrement the filter's refcount.

Initially, we called it in free_task() called from the failure path, but
the commit 3a15fb6ed9 ("seccomp: release filter after task is fully
dead") moved it to release_task() to notify user space as early as possible
that the filter is no longer used.

To keep the change and current seccomp refcount semantics, let's move
copy_seccomp() just after the signal check and add a WARN_ON_ONCE() in
free_task() for future debugging.

[0]:
unreferenced object 0xffff8880063add00 (size 256):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.914s)
  hex dump (first 32 bytes):
    01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
  backtrace:
    do_seccomp (./include/linux/slab.h:600 ./include/linux/slab.h:733 kernel/seccomp.c:666 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffffc90000035000 (size 4096):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 05 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    __vmalloc_node_range (mm/vmalloc.c:3226)
    __vmalloc_node (mm/vmalloc.c:3261 (discriminator 4))
    bpf_prog_alloc_no_stats (kernel/bpf/core.c:91)
    bpf_prog_alloc (kernel/bpf/core.c:129)
    bpf_prog_create_from_user (net/core/filter.c:1414)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffff888003fa1000 (size 1024):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    bpf_prog_alloc_no_stats (./include/linux/slab.h:600 ./include/linux/slab.h:733 kernel/bpf/core.c:95)
    bpf_prog_alloc (kernel/bpf/core.c:129)
    bpf_prog_create_from_user (net/core/filter.c:1414)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffff888006360240 (size 16):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 16 bytes):
    01 00 37 00 76 65 72 6c e0 83 01 06 80 88 ff ff  ..7.verl........
  backtrace:
    bpf_prog_store_orig_filter (net/core/filter.c:1137)
    bpf_prog_create_from_user (net/core/filter.c:1428)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffff8880060183e0 (size 8):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 8 bytes):
    06 00 00 00 00 00 ff 7f                          ........
  backtrace:
    kmemdup (mm/util.c:129)
    bpf_prog_store_orig_filter (net/core/filter.c:1144)
    bpf_prog_create_from_user (net/core/filter.c:1428)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)

[1]: https://syzkaller.appspot.com/bug?id=2809bb0ac77ad9aa3f4afe42d6a610aba594a987

[2]:

void main(void)
{
	struct sock_filter filter[] = {
		BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
	};
	struct sock_fprog fprog = {
		.len = sizeof(filter) / sizeof(filter[0]),
		.filter = filter,
	};
	long i, pid;

	syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0, &fprog);

	for (i = 0; i < 2; i++) {
		pid = syscall(__NR_clone, CLONE_NEWNET | SIGKILL, NULL, NULL, 0);
		if (pid == 0)
			return;
	}
}

Fixes: 3a15fb6ed9 ("seccomp: release filter after task is fully dead")
Reported-by: syzbot+ab17848fe269b573eb71@syzkaller.appspotmail.com
Reported-by: Ayushman Dutta <ayudutta@amazon.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220823154532.82913-1-kuniyu@amazon.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:14:00 +01:00
..
bpf bpf: Do not copy spin lock field from user in bpf_selem_alloc 2022-12-08 11:28:39 +01:00
cgroup memcg: fix possible use-after-free in memcg_write_event_control() 2022-12-14 11:37:19 +01:00
configs
debug lockdown: also lock down previous kgdb use 2022-05-25 09:57:37 +02:00
dma swiotlb: max mapping size takes min align mask into account 2022-10-05 10:39:40 +02:00
entry lockdep: Fix -Wunused-parameter for _THIS_IP_ 2022-09-20 12:39:42 +02:00
events perf: Fix perf_pending_task() UaF 2022-12-19 12:36:43 +01:00
gcov gcov: clang: fix the buffer overflow issue 2022-12-02 17:41:09 +01:00
irq genirq: Take the proposed affinity at face value if force==true 2022-12-02 17:41:12 +01:00
kcsan LKMM updates: 2021-09-02 13:00:15 -07:00
livepatch livepatch: fix race between fork and KLP transition 2022-10-26 12:34:30 +02:00
locking lockdep: Fix -Wunused-parameter for _THIS_IP_ 2022-09-20 12:39:42 +02:00
power PM: hibernate: Allow hybrid sleep to work with s2idle 2022-11-03 23:59:17 +09:00
printk printk: wake waiters for safe and NMI contexts 2022-06-09 10:22:49 +02:00
rcu rcu-tasks: Convert RCU_LOCKDEP_WARN() to WARN_ONCE() 2022-10-26 12:35:29 +02:00
sched io_uring: move to separate directory 2022-12-14 11:37:31 +01:00
time timekeeping: contribute wall clock to rng on time change 2022-08-17 14:24:24 +02:00
trace tracing: Free buffers when a used dynamic event is removed 2022-12-08 11:28:43 +01:00
.gitignore
acct.c kernel/acct.c: use dedicated helper to access rlimit values 2021-09-08 11:50:26 -07:00
async.c Revert "module, async: async_synchronize_full() on module init iff async is used" 2022-02-23 12:03:07 +01:00
audit.c audit: improve audit queue handling when "audit=1" on cmdline 2022-02-08 18:34:03 +01:00
audit.h audit: log AUDIT_TIME_* records only from rules 2022-04-08 14:23:06 +02:00
audit_fsnotify.c audit: fix potential double free on error path from fsnotify_add_inode_mark 2022-08-31 17:16:33 +02:00
audit_tree.c audit: move put_tree() to avoid trim_trees refcount underflow and UAF 2021-08-24 18:52:36 -04:00
audit_watch.c
auditfilter.c
auditsc.c audit: log AUDIT_TIME_* records only from rules 2022-04-08 14:23:06 +02:00
backtracetest.c
bounds.c
capability.c
cfi.c cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle 2022-06-22 14:22:04 +02:00
compat.c arch: remove compat_alloc_user_space 2021-09-08 15:32:35 -07:00
configs.c
context_tracking.c
cpu.c random: clear fast pool, crng, and batches in cpuhp bring up 2022-05-30 09:29:09 +02:00
cpu_pm.c PM: cpu: Make notifier chain use a raw_spinlock_t 2021-08-16 18:55:32 +02:00
crash_core.c kernel/crash_core: suppress unknown crashkernel parameter warning 2021-12-29 12:28:49 +01:00
crash_dump.c
cred.c ucounts: Base set_cred_ucounts changes on the real user 2022-02-23 12:03:20 +01:00
delayacct.c
dma.c
exec_domain.c
exit.c fix race between exit_itimers() and /proc/pid/timers 2022-07-21 21:24:11 +02:00
extable.c
fail_function.c
fork.c seccomp: Move copy_seccomp() to no failure path. 2022-12-31 13:14:00 +01:00
freezer.c
futex.c futex: Remove unused variable 'vpid' in futex_proxy_trylock_atomic() 2021-09-03 23:00:22 +02:00
gen_kheaders.sh
groups.c
hung_task.c
iomem.c
irq_work.c
jump_label.c jump_label: Fix jump_label_text_reserved() vs __init 2021-07-05 10:46:20 +02:00
kallsyms.c module: add printk formats to add module build ID to stacktraces 2021-07-08 11:48:22 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/rwlock: Provide RT variant 2021-08-17 17:50:51 +02:00
Kconfig.preempt
kcov.c
kexec.c kexec: avoid compat_alloc_user_space 2021-09-08 15:32:34 -07:00
kexec_core.c Merge branch 'rework/printk_safe-removal' into for-linus 2021-08-30 16:36:10 +02:00
kexec_elf.c
kexec_file.c ima: force signature verification when CONFIG_KEXEC_SIG is configured 2022-07-21 21:24:29 +02:00
kexec_internal.h
kheaders.c
kmod.c
kprobes.c kprobes: Skip clearing aggrprobe's post_handler in kprobe-on-ftrace case 2022-11-26 09:24:50 +01:00
ksysfs.c
kthread.c
latencytop.c
Makefile static_call: Don't make __static_call_return0 static 2022-04-13 20:59:28 +02:00
module-internal.h
module.c module: fix [e_shstrndx].sh_size=0 OOB access 2022-07-12 16:35:09 +02:00
module_signature.c
module_signing.c
notifier.c notifier: Remove atomic_notifier_call_chain_robust() 2021-08-16 18:55:32 +02:00
nsproxy.c memcg: enable accounting for new namesapces and struct nsproxy 2021-09-03 09:58:12 -07:00
padata.c padata: Remove repeated verbose license text 2021-08-27 16:30:18 +08:00
panic.c Merge branch 'rework/printk_safe-removal' into for-linus 2021-08-30 16:36:10 +02:00
params.c params: lift param_set_uint_minmax to common code 2021-08-16 14:42:22 +02:00
pid.c kernel/pid.c: implement additional checks upon pidfd_create() parameters 2021-08-10 12:53:07 +02:00
pid_namespace.c memcg: enable accounting for new namesapces and struct nsproxy 2021-09-03 09:58:12 -07:00
profile.c profiling: fix shift too large makes kernel panic 2022-08-17 14:24:04 +02:00
ptrace.c ptrace: Reimplement PTRACE_KILL by always sending SIGKILL 2022-06-09 10:22:29 +02:00
range.c
reboot.c
regset.c
relay.c
resource.c kernel/resource: fix kfree() of bootmem memory again 2022-04-08 14:23:43 +02:00
resource_kunit.c
rseq.c rseq: Remove broken uapi field layout on 32-bit little endian 2022-04-08 14:23:10 +02:00
scftorture.c scftorture: Fix distribution of short handler delays 2022-06-09 10:22:46 +02:00
scs.c scs: Release kasan vmalloc poison in scs_free process 2021-11-18 19:16:29 +01:00
seccomp.c seccomp: Invalidate seccomp mode to catch death failures 2022-02-16 12:56:38 +01:00
signal.c signal handling: don't use BUG_ON() for debugging 2022-07-21 21:24:42 +02:00
smp.c locking/csd_lock: Change csdlock_debug from early_param to __setup 2022-08-17 14:24:24 +02:00
smpboot.c smpboot: Replace deprecated CPU-hotplug functions. 2021-08-10 14:57:42 +02:00
smpboot.h
softirq.c genirq: Change force_irqthreads to a static key 2021-08-10 22:50:07 +02:00
stackleak.c gcc-plugins/stackleak: Use noinstr in favor of notrace 2022-02-23 12:03:07 +01:00
stacktrace.c stacktrace: move filter_irq_stacks() to kernel/stacktrace.c 2022-04-13 20:59:28 +02:00
static_call.c static_call: Don't make __static_call_return0 static 2022-04-13 20:59:28 +02:00
static_call_inline.c static_call: Don't make __static_call_return0 static 2022-04-13 20:59:28 +02:00
stop_machine.c
sys.c ucounts: Move RLIMIT_NPROC handling after set_user 2022-02-23 12:03:20 +01:00
sys_ni.c kernel/sys_ni: add compat entry for fadvise64_64 2022-08-31 17:16:33 +02:00
sysctl-test.c
sysctl.c proc: proc_skip_spaces() shouldn't think it is working on C strings 2022-12-08 11:28:45 +01:00
task_work.c
taskstats.c
test_kprobes.c
torture.c torture: Replace deprecated CPU-hotplug functions. 2021-08-10 10:48:07 -07:00
tracepoint.c tracepoint: Fix kerneldoc comments 2021-08-16 11:39:51 -04:00
tsacct.c taskstats: Cleanup the use of task->exit_code 2022-01-27 11:05:35 +01:00
ucount.c ucounts: Handle wrapping in is_ucounts_overlimit 2022-02-23 12:03:20 +01:00
uid16.c
uid16.h
umh.c
up.c
user-return-notifier.c
user.c fs/epoll: use a per-cpu counter for user's watches count 2021-09-08 11:50:27 -07:00
user_namespace.c ucounts: Fix systemd LimitNPROC with private users regression 2022-03-08 19:12:42 +01:00
usermode_driver.c
utsname.c
utsname_sysctl.c
watch_queue.c watch_queue: Fix missing locking in add_watch_to_object() 2022-08-03 12:03:43 +02:00
watchdog.c watchdog: export lockup_detector_reconfigure 2022-08-25 11:40:43 +02:00
watchdog_hld.c
workqueue.c workqueue: don't skip lockdep work dependency in cancel_work_sync() 2022-09-28 11:11:56 +02:00
workqueue_internal.h workqueue: Assign a color to barrier work items 2021-08-17 07:49:10 -10:00