======================================================
WARNING: possible circular locking dependency detected
4.14.176-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/12706 is trying to acquire lock:
(&sig->cred_guard_mutex){+.+.}, at: [<ffffffff81a45d9f>] lock_trace+0x3f/0xc0 fs/proc/base.c:407
but task is already holding lock:
(&p->lock){+.+.}, at: [<ffffffff8192f0ba>] seq_read+0xba/0x1160 fs/seq_file.c:165
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&p->lock){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
seq_read+0xba/0x1160 fs/seq_file.c:165
proc_reg_read+0xf2/0x160 fs/proc/inode.c:217
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e3/0x5a0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x41d/0x870 fs/splice.c:416
do_splice_to+0xfb/0x150 fs/splice.c:880
splice_direct_to_actor+0x20a/0x730 fs/splice.c:952
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x469/0xaf0 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1502 [inline]
SyS_sendfile64+0xff/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #2 (sb_writers#3){.+.+}:
percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
__sb_start_write+0x1a1/0x2e0 fs/super.c:1363
sb_start_write include/linux/fs.h:1549 [inline]
mnt_want_write+0x3a/0xb0 fs/namespace.c:386
ovl_xattr_set+0x4d/0x270 fs/overlayfs/inode.c:214
ovl_posix_acl_xattr_set+0x3f9/0x830 fs/overlayfs/super.c:762
__vfs_setxattr+0xdc/0x130 fs/xattr.c:150
__vfs_setxattr_noperm+0xfd/0x3c0 fs/xattr.c:181
vfs_setxattr+0xba/0xe0 fs/xattr.c:224
setxattr+0x1a9/0x300 fs/xattr.c:453
path_setxattr+0x118/0x130 fs/xattr.c:472
SYSC_lsetxattr fs/xattr.c:494 [inline]
SyS_lsetxattr+0x33/0x40 fs/xattr.c:490
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #1 (&ovl_i_mutex_dir_key[depth]){++++}:
down_read+0x37/0xa0 kernel/locking/rwsem.c:24
inode_lock_shared include/linux/fs.h:729 [inline]
do_last fs/namei.c:3333 [inline]
path_openat+0x185a/0x3c50 fs/namei.c:3569
do_filp_open+0x18e/0x250 fs/namei.c:3603
do_open_execat+0xda/0x430 fs/exec.c:849
do_execveat_common.isra.0+0x694/0x1c70 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+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #0 (&sig->cred_guard_mutex){+.+.}:
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
lock_trace+0x3f/0xc0 fs/proc/base.c:407
proc_pid_stack+0x10b/0x240 fs/proc/base.c:457
proc_single_show+0xe7/0x150 fs/proc/base.c:761
seq_read+0x4d2/0x1160 fs/seq_file.c:237
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e3/0x5a0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
do_preadv+0x161/0x200 fs/read_write.c:1065
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
other info that might help us debug this:
Chain exists of:
&sig->cred_guard_mutex --> sb_writers#3 --> &p->lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&p->lock);
lock(sb_writers#3);
lock(&p->lock);
lock(&sig->cred_guard_mutex);
*** DEADLOCK ***
1 lock held by syz-executor.1/12706:
#0: (&p->lock){+.+.}, at: [<ffffffff8192f0ba>] seq_read+0xba/0x1160 fs/seq_file.c:165
stack backtrace:
CPU: 1 PID: 12706 Comm: syz-executor.1 Not tainted 4.14.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x13e/0x194 lib/dump_stack.c:58
print_circular_bug.isra.0.cold+0x1c4/0x282 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+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
lock_trace+0x3f/0xc0 fs/proc/base.c:407
proc_pid_stack+0x10b/0x240 fs/proc/base.c:457
proc_single_show+0xe7/0x150 fs/proc/base.c:761
seq_read+0x4d2/0x1160 fs/seq_file.c:237
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e3/0x5a0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
do_preadv+0x161/0x200 fs/read_write.c:1065
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c889
RSP: 002b:00007f5f5eeffc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007f5f5ef006d4 RCX: 000000000045c889
RDX: 000000000000037d RSI: 0000000020000500 RDI: 0000000000000008
RBP: 000000000076c180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000085c R14: 00000000004cb214 R15: 000000000076c18c
XFS (loop0): Invalid superblock magic number
XFS (loop0): Invalid superblock magic number