======================================================
WARNING: possible circular locking dependency detected
5.0.0+ #20 Not tainted
------------------------------------------------------
syz-executor.2/27690 is trying to acquire lock:
00000000cc85d908 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline]
00000000cc85d908 (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 fs/pipe.c:930
but task is already holding lock:
00000000d6e9432a (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline]
00000000d6e9432a (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&sig->cred_guard_mutex){+.+.}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_interruptible_nested+0x16/0x20 kernel/locking/mutex.c:1109
proc_pid_attr_write+0x200/0x580 fs/proc/base.c:2558
__vfs_write+0x8d/0x110 fs/read_write.c:485
__kernel_write+0x110/0x3b0 fs/read_write.c:506
write_pipe_buf+0x15d/0x1f0 fs/splice.c:793
splice_from_pipe_feed fs/splice.c:499 [inline]
__splice_from_pipe+0x395/0x7d0 fs/splice.c:623
splice_from_pipe+0x108/0x170 fs/splice.c:658
default_file_splice_write+0x3c/0x90 fs/splice.c:805
do_splice_from fs/splice.c:847 [inline]
do_splice+0x70a/0x13c0 fs/splice.c:1154
__do_sys_splice fs/splice.c:1424 [inline]
__se_sys_splice fs/splice.c:1404 [inline]
__x64_sys_splice+0x2c6/0x330 fs/splice.c:1404
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&pipe->mutex/1){+.+.}:
check_prevs_add kernel/locking/lockdep.c:2333 [inline]
validate_chain kernel/locking/lockdep.c:2714 [inline]
__lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
__pipe_lock fs/pipe.c:83 [inline]
fifo_open+0x159/0xb00 fs/pipe.c:930
do_dentry_open+0x488/0x1160 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3416 [inline]
path_openat+0x10e9/0x46e0 fs/namei.c:3533
do_filp_open+0x1a1/0x280 fs/namei.c:3563
do_open_execat+0x137/0x690 fs/exec.c:856
__do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758
do_execveat_common fs/exec.c:1865 [inline]
do_execve fs/exec.c:1882 [inline]
__do_sys_execve fs/exec.c:1958 [inline]
__se_sys_execve fs/exec.c:1953 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:1953
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sig->cred_guard_mutex);
lock(&pipe->mutex/1);
lock(&sig->cred_guard_mutex);
lock(&pipe->mutex/1);
*** DEADLOCK ***
1 lock held by syz-executor.2/27690:
#0: 00000000d6e9432a (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline]
#0: 00000000d6e9432a (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750
stack backtrace:
CPU: 1 PID: 27690 Comm: syz-executor.2 Not tainted 5.0.0+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1571
check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2220
check_prevs_add kernel/locking/lockdep.c:2333 [inline]
validate_chain kernel/locking/lockdep.c:2714 [inline]
__lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
__pipe_lock fs/pipe.c:83 [inline]
fifo_open+0x159/0xb00 fs/pipe.c:930
do_dentry_open+0x488/0x1160 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3416 [inline]
path_openat+0x10e9/0x46e0 fs/namei.c:3533
do_filp_open+0x1a1/0x280 fs/namei.c:3563
do_open_execat+0x137/0x690 fs/exec.c:856
__do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758
do_execveat_common fs/exec.c:1865 [inline]
do_execve fs/exec.c:1882 [inline]
__do_sys_execve fs/exec.c:1958 [inline]
__se_sys_execve fs/exec.c:1953 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:1953
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457f29
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f201dd43c78 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457f29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000280
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f201dd446d4
R13: 00000000004be513 R14: 00000000004cee00 R15: 00000000ffffffff