Pu Lehui 222bd95c89 bpf, cgroup: Fix kernel BUG in purge_effective_progs ... [ Upstream commit 7d6620f107 ] Syzkaller reported a triggered kernel BUG as follows: ------------[ cut here ]------------ kernel BUG at kernel/bpf/cgroup.c:925! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 194 Comm: detach Not tainted 5.19.0-14184-g69dac8e431af #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:__cgroup_bpf_detach+0x1f2/0x2a0 Code: 00 e8 92 60 30 00 84 c0 75 d8 4c 89 e0 31 f6 85 f6 74 19 42 f6 84 28 48 05 00 00 02 75 0e 48 8b 80 c0 00 00 00 48 85 c0 75 e5 <0f> 0b 48 8b 0c5 RSP: 0018:ffffc9000055bdb0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff888100ec0800 RCX: ffffc900000f1000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888100ec4578 RBP: 0000000000000000 R08: ffff888100ec0800 R09: 0000000000000040 R10: 0000000000000000 R11: 0000000000000000 R12: ffff888100ec4000 R13: 000000000000000d R14: ffffc90000199000 R15: ffff888100effb00 FS: 00007f68213d2b80(0000) GS:ffff88813bc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f74a0e5850 CR3: 0000000102836000 CR4: 00000000000006e0 Call Trace: <TASK> cgroup_bpf_prog_detach+0xcc/0x100 __sys_bpf+0x2273/0x2a00 __x64_sys_bpf+0x17/0x20 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f68214dbcb9 Code: 08 44 89 e0 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff8 RSP: 002b:00007ffeb487db68 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007f68214dbcb9 RDX: 0000000000000090 RSI: 00007ffeb487db70 RDI: 0000000000000009 RBP: 0000000000000003 R08: 0000000000000012 R09: 0000000b00000003 R10: 00007ffeb487db70 R11: 0000000000000246 R12: 00007ffeb487dc20 R13: 0000000000000004 R14: 0000000000000001 R15: 000055f74a1011b0 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- Repetition steps: For the following cgroup tree, root | cg1 | cg2 1. attach prog2 to cg2, and then attach prog1 to cg1, both bpf progs attach type is NONE or OVERRIDE. 2. write 1 to /proc/thread-self/fail-nth for failslab. 3. detach prog1 for cg1, and then kernel BUG occur. Failslab injection will cause kmalloc fail and fall back to purge_effective_progs. The problem is that cg2 have attached another prog, so when go through cg2 layer, iteration will add pos to 1, and subsequent operations will be skipped by the following condition, and cg will meet NULL in the end. `if (pos && !(cg->bpf.flags[atype] & BPF_F_ALLOW_MULTI))` The NULL cg means no link or prog match, this is as expected, and it's not a bug. So here just skip the no match situation. Fixes: 4c46091ee9 ("bpf: Fix KASAN use-after-free Read in compute_effective_progs") Signed-off-by: Pu Lehui <pulehui@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220813134030.1972696-1-pulehui@huawei.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-09-08 12:28:01 +02:00
..
preload	libbpf: Move BPF_SEQ_PRINTF and BPF_SNPRINTF to bpf_helpers.h	2021-05-26 10:45:41 -07:00
arraymap.c	bpf: Acquire map uref in .init_seq_private for array map iterator	2022-08-25 11:40:03 +02:00
bpf_inode_storage.c	bpf: Fix spelling mistakes	2021-05-24 21:13:05 -07:00
bpf_iter.c	bpf: Refactor BPF_PROG_RUN into a function	2021-08-17 00:45:07 +02:00
bpf_local_storage.c	bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]	2021-02-26 11:51:48 -08:00
bpf_lru_list.c	bpf_lru_list: Read double-checked variable once without lock	2021-02-10 15:54:26 -08:00
bpf_lru_list.h	bpf: Fix a typo "inacitve" -> "inactive"	2020-04-06 21:54:10 +02:00
bpf_lsm.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next	2021-06-17 11:54:56 -07:00
bpf_struct_ops.c	bpf: Handle return value of BPF_PROG_TYPE_STRUCT_OPS prog	2021-09-14 11:09:50 -07:00
bpf_struct_ops_types.h
bpf_task_storage.c	bpf: Consolidate task_struct BTF_ID declarations	2021-08-25 10:37:05 -07:00
btf.c	bpf: Fix calling global functions from BPF_PROG_TYPE_EXT programs	2022-06-25 15:18:40 +02:00
cgroup.c	bpf, cgroup: Fix kernel BUG in purge_effective_progs	2022-09-08 12:28:01 +02:00
core.c	bpf: Make sure mac_header was set before using it	2022-07-29 17:25:24 +02:00
cpumap.c	bpf: cpumap: Implement generic cpumap	2021-07-07 20:01:45 -07:00
devmap.c	bpf, devmap: Exclude XDP broadcast to master device	2021-08-09 23:25:14 +02:00
disasm.c	bpf: Relicense disassembler as GPL-2.0-only OR BSD-2-Clause	2021-09-02 14:49:23 +02:00
disasm.h	bpf: Relicense disassembler as GPL-2.0-only OR BSD-2-Clause	2021-09-02 14:49:23 +02:00
dispatcher.c	bpf: Remove bpf_image tree	2020-03-13 12:49:52 -07:00
hashtab.c	bpf: Acquire map uref in .init_seq_private for hash map iterator	2022-08-25 11:40:03 +02:00
helpers.c	bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.	2022-05-01 17:22:26 +02:00
inode.c	bpf: Fix mount source show for bpffs	2022-01-27 11:05:26 +01:00
Kconfig	sock_map: Relax config dependency to CONFIG_NET	2021-07-15 18:17:49 -07:00
local_storage.c	bpf: Increase supported cgroup storage value size	2021-07-27 15:59:29 -07:00
lpm_trie.c	bpf: Allow RCU-protected lookups to happen from bh context	2021-06-24 19:41:15 +02:00
Makefile	bpf: Enable task local storage for tracing programs	2021-02-26 11:51:47 -08:00
map_in_map.c	bpf: Remember BTF of inner maps.	2021-07-15 22:31:10 +02:00
map_in_map.h	bpf: Add map_meta_equal map ops	2020-08-28 15:41:30 +02:00
map_iter.c	bpf: Introduce MEM_RDONLY flag	2022-05-01 17:22:24 +02:00
net_namespace.c	bpf: Add support for forced LINK_DETACH command	2020-08-01 20:38:28 -07:00
offload.c	bpf, offload: Replace bitwise AND by logical AND in bpf_prog_offload_info_fill	2020-02-17 16:53:49 +01:00
percpu_freelist.c	bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI	2020-10-06 00:04:11 +02:00
percpu_freelist.h	bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI	2020-10-06 00:04:11 +02:00
prog_iter.c	bpf: Refactor bpf_iter_reg to have separate seq_info member	2020-07-25 20:16:32 -07:00
queue_stack_maps.c	bpf: Eliminate rlimit-based memory accounting for queue_stack_maps maps	2020-12-02 18:32:46 -08:00
reuseport_array.c	bpf: Fix spelling mistakes	2021-05-24 21:13:05 -07:00
ringbuf.c	bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.	2022-05-01 17:22:26 +02:00
stackmap.c	bpf: Fix excessive memory allocation in stack_map_alloc()	2022-06-06 08:43:42 +02:00
syscall.c	bpf: Restrict bpf_sys_bpf to CAP_PERFMON	2022-09-08 12:28:01 +02:00
sysfs_btf.c	bpf: Load and verify kernel module BTFs	2020-11-10 15:25:53 -08:00
task_iter.c	bpf: Consolidate task_struct BTF_ID declarations	2021-08-25 10:37:05 -07:00
tnum.c	bpf, tnums: Provably sound, faster, and more precise algorithm for tnum_mul	2021-06-01 13:34:15 +02:00
trampoline.c	bpf: Fix potential array overflow in bpf_trampoline_get_progs()	2022-06-06 08:43:42 +02:00
verifier.c	bpf: Don't use tnum_range on array range checking for poke descriptors	2022-08-31 17:16:51 +02:00