======================================================
[ INFO: possible circular locking dependency detected ]
4.9.141+ #23 Not tainted
-------------------------------------------------------
syz-executor.5/3786 is trying to acquire lock:
(&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff8166030b>] do_io_accounting+0x1fb/0x7e0 fs/proc/base.c:2690
but task is already holding lock:
(&p->lock){+.+.+.}, at: [<ffffffff8158080d>] seq_read+0xdd/0x12d0 fs/seq_file.c:178
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
__mutex_lock_common kernel/locking/mutex.c:521 [inline]
mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621
seq_read+0xdd/0x12d0 fs/seq_file.c:178
proc_reg_read+0xfd/0x180 fs/proc/inode.c:203
do_loop_readv_writev.part.1+0xd5/0x280 fs/read_write.c:718
do_loop_readv_writev fs/read_write.c:707 [inline]
do_readv_writev+0x56e/0x7b0 fs/read_write.c:873
vfs_readv+0x84/0xc0 fs/read_write.c:897
kernel_readv fs/splice.c:363 [inline]
default_file_splice_read+0x451/0x7f0 fs/splice.c:435
do_splice_to+0x10c/0x170 fs/splice.c:899
do_splice fs/splice.c:1192 [inline]
SYSC_splice fs/splice.c:1416 [inline]
SyS_splice+0x10d2/0x14d0 fs/splice.c:1399
do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
__mutex_lock_common kernel/locking/mutex.c:521 [inline]
mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621
__pipe_lock fs/pipe.c:87 [inline]
fifo_open+0x15c/0x9e0 fs/pipe.c:921
do_dentry_open+0x3ef/0xc90 fs/open.c:766
vfs_open+0x11c/0x210 fs/open.c:879
do_last fs/namei.c:3410 [inline]
path_openat+0x542/0x2790 fs/namei.c:3534
do_filp_open+0x197/0x270 fs/namei.c:3568
do_open_execat+0x10f/0x640 fs/exec.c:844
do_execveat_common.isra.14+0x687/0x1ed0 fs/exec.c:1723
compat_do_execve fs/exec.c:1856 [inline]
C_SYSC_execve fs/exec.c:1931 [inline]
compat_SyS_execve+0x48/0x60 fs/exec.c:1927
do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
check_prev_add kernel/locking/lockdep.c:1828 [inline]
check_prevs_add kernel/locking/lockdep.c:1938 [inline]
validate_chain kernel/locking/lockdep.c:2265 [inline]
__lock_acquire+0x3189/0x4a10 kernel/locking/lockdep.c:3345
lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
__mutex_lock_common kernel/locking/mutex.c:521 [inline]
mutex_lock_killable_nested+0xcc/0x9f0 kernel/locking/mutex.c:641
do_io_accounting+0x1fb/0x7e0 fs/proc/base.c:2690
proc_tgid_io_accounting+0x22/0x30 fs/proc/base.c:2739
proc_single_show+0xfd/0x170 fs/proc/base.c:785
seq_read+0x4b6/0x12d0 fs/seq_file.c:240
__vfs_read+0x115/0x560 fs/read_write.c:449
vfs_read+0x124/0x390 fs/read_write.c:472
SYSC_pread64 fs/read_write.c:626 [inline]
SyS_pread64+0x145/0x170 fs/read_write.c:613
sys32_pread+0x39/0x50 arch/x86/ia32/sys_ia32.c:179
do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
other info that might help us debug this:
Chain exists of:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&p->lock);
lock(&pipe->mutex/1);
lock(&p->lock);
lock(&sig->cred_guard_mutex);
*** DEADLOCK ***
PF_BRIDGE: RTM_NEWNEIGH with invalid ifindex
PF_BRIDGE: RTM_NEWNEIGH with unknown ifindex
1 lock held by syz-executor.5/3786:
#0: (&p->lock){+.+.+.}, at: [<ffffffff8158080d>] seq_read+0xdd/0x12d0 fs/seq_file.c:178
stack backtrace:
CPU: 1 PID: 3786 Comm: syz-executor.5 Not tainted 4.9.141+ #23
ffff88019da67608 ffffffff81b42e79 ffffffff83ca9f30 ffffffff83ca4fe0
ffffffff83ca2fd0 ffff8801c661d010 ffff8801c661c740 ffff88019da67650
ffffffff813fee40 0000000000000001 00000000c661cff0 0000000000000001
Call Trace:
[<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff813fee40>] print_circular_bug.cold.36+0x2f7/0x432 kernel/locking/lockdep.c:1202
[<ffffffff8120a539>] check_prev_add kernel/locking/lockdep.c:1828 [inline]
[<ffffffff8120a539>] check_prevs_add kernel/locking/lockdep.c:1938 [inline]
[<ffffffff8120a539>] validate_chain kernel/locking/lockdep.c:2265 [inline]
[<ffffffff8120a539>] __lock_acquire+0x3189/0x4a10 kernel/locking/lockdep.c:3345
[<ffffffff8120c8d0>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
[<ffffffff8280c45c>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
[<ffffffff8280c45c>] mutex_lock_killable_nested+0xcc/0x9f0 kernel/locking/mutex.c:641
[<ffffffff8166030b>] do_io_accounting+0x1fb/0x7e0 fs/proc/base.c:2690
[<ffffffff81660912>] proc_tgid_io_accounting+0x22/0x30 fs/proc/base.c:2739
[<ffffffff8165e66d>] proc_single_show+0xfd/0x170 fs/proc/base.c:785
[<ffffffff81580be6>] seq_read+0x4b6/0x12d0 fs/seq_file.c:240
[<ffffffff81507b25>] __vfs_read+0x115/0x560 fs/read_write.c:449
[<ffffffff8150a7a4>] vfs_read+0x124/0x390 fs/read_write.c:472
[<ffffffff8150ebf5>] SYSC_pread64 fs/read_write.c:626 [inline]
[<ffffffff8150ebf5>] SyS_pread64+0x145/0x170 fs/read_write.c:613
[<ffffffff810c6349>] sys32_pread+0x39/0x50 arch/x86/ia32/sys_ia32.c:179
[<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
[<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
[<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
netlink: 188 bytes leftover after parsing attributes in process `syz-executor.1'.
netlink: 188 bytes leftover after parsing attributes in process `syz-executor.1'.
audit: type=1400 audit(1574634891.314:36): avc: denied { getopt } for pid=4010 comm="syz-executor.1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1