======================================================
WARNING: possible circular locking dependency detected
4.14.85+ #15 Not tainted
------------------------------------------------------
syz-executor2/10287 is trying to acquire lock:
(&sig->cred_guard_mutex){+.+.}, at: [<ffffffffa829f867>] do_io_accounting+0x1d7/0x770 fs/proc/base.c:2731
but task is already holding lock:
(&p->lock){+.+.}, at: [<ffffffffa81d19d4>] seq_read+0xd4/0x11d0 fs/seq_file.c:165
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&p->lock){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893
seq_read+0xd4/0x11d0 fs/seq_file.c:165
proc_reg_read+0xef/0x170 fs/proc/inode.c:217
do_loop_readv_writev fs/read_write.c:698 [inline]
do_iter_read+0x3cc/0x580 fs/read_write.c:922
vfs_readv+0xe6/0x150 fs/read_write.c:984
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x495/0x860 fs/splice.c:416
do_splice_to+0x102/0x150 fs/splice.c:880
do_splice fs/splice.c:1173 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0xf4d/0x12a0 fs/splice.c:1382
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #1 (&pipe->mutex/1){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893
__pipe_lock fs/pipe.c:88 [inline]
fifo_open+0x156/0x9d0 fs/pipe.c:921
do_dentry_open+0x426/0xda0 fs/open.c:764
vfs_open+0x11c/0x210 fs/open.c:878
do_last fs/namei.c:3455 [inline]
path_openat+0x5f9/0x2930 fs/namei.c:3597
do_filp_open+0x197/0x270 fs/namei.c:3631
do_open_execat+0x10d/0x5b0 fs/exec.c:849
do_execveat_common.isra.14+0x6cb/0x1d60 fs/exec.c:1740
do_execve fs/exec.c:1847 [inline]
SYSC_execve fs/exec.c:1928 [inline]
SyS_execve+0x34/0x40 fs/exec.c:1923
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #0 (&sig->cred_guard_mutex){+.+.}:
lock_acquire+0x10f/0x380 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893
do_io_accounting+0x1d7/0x770 fs/proc/base.c:2731
proc_single_show+0xf1/0x160 fs/proc/base.c:762
seq_read+0x4e0/0x11d0 fs/seq_file.c:237
do_loop_readv_writev fs/read_write.c:698 [inline]
do_iter_read+0x3cc/0x580 fs/read_write.c:922
vfs_readv+0xe6/0x150 fs/read_write.c:984
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x495/0x860 fs/splice.c:416
do_splice_to+0x102/0x150 fs/splice.c:880
splice_direct_to_actor+0x21d/0x750 fs/splice.c:952
do_splice_direct+0x17b/0x220 fs/splice.c:1061
do_sendfile+0x4a1/0xb50 fs/read_write.c:1438
SYSC_sendfile64 fs/read_write.c:1499 [inline]
SyS_sendfile64+0x11f/0x140 fs/read_write.c:1485
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
other info that might help us debug this:
Chain exists of:
&sig->cred_guard_mutex --> &pipe->mutex/1 --> &p->lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&p->lock);
lock(&pipe->mutex/1);
lock(&p->lock);
lock(&sig->cred_guard_mutex);
*** DEADLOCK ***
1 lock held by syz-executor2/10287:
#0: (&p->lock){+.+.}, at: [<ffffffffa81d19d4>] seq_read+0xd4/0x11d0 fs/seq_file.c:165
stack backtrace:
CPU: 0 PID: 10287 Comm: syz-executor2 Not tainted 4.14.85+ #15
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0xb9/0x11b lib/dump_stack.c:53
print_circular_bug.isra.18.cold.43+0x2d3/0x40c kernel/locking/lockdep.c:1258
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2ff9/0x4320 kernel/locking/lockdep.c:3487
lock_acquire+0x10f/0x380 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893
do_io_accounting+0x1d7/0x770 fs/proc/base.c:2731
proc_single_show+0xf1/0x160 fs/proc/base.c:762
seq_read+0x4e0/0x11d0 fs/seq_file.c:237
do_loop_readv_writev fs/read_write.c:698 [inline]
do_iter_read+0x3cc/0x580 fs/read_write.c:922
vfs_readv+0xe6/0x150 fs/read_write.c:984
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x495/0x860 fs/splice.c:416
do_splice_to+0x102/0x150 fs/splice.c:880
splice_direct_to_actor+0x21d/0x750 fs/splice.c:952
do_splice_direct+0x17b/0x220 fs/splice.c:1061
do_sendfile+0x4a1/0xb50 fs/read_write.c:1438
SYSC_sendfile64 fs/read_write.c:1499 [inline]
SyS_sendfile64+0x11f/0x140 fs/read_write.c:1485
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457569
RSP: 002b:00007f8d1aaf0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457569
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 00007f8d1aaf16d4
R13: 00000000004c3c2a R14: 00000000004d6230 R15: 00000000ffffffff