======================================================
WARNING: possible circular locking dependency detected
4.14.174-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/31257 is trying to acquire lock:
 (&sig->cred_guard_mutex){+.+.}, at: [<ffffffff81a45adf>] lock_trace+0x3f/0xc0 fs/proc/base.c:407

but task is already holding lock:
 (&p->lock){+.+.}, at: [<ffffffff8192efba>] 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#4){.+.+}:
       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:1548 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:386
       ovl_create_object+0x75/0x1d0 fs/overlayfs/dir.c:538
       lookup_open+0x10e8/0x1750 fs/namei.c:3241
       do_last fs/namei.c:3334 [inline]
       path_openat+0xfc1/0x3c50 fs/namei.c:3569
       do_filp_open+0x18e/0x250 fs/namei.c:3603
       do_sys_open+0x29d/0x3f0 fs/open.c:1081
       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:728 [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
       open_exec+0x32/0x60 fs/exec.c:881
       load_script+0x4ce/0x730 fs/binfmt_script.c:140
       search_binary_handler fs/exec.c:1638 [inline]
       search_binary_handler+0x139/0x6c0 fs/exec.c:1616
       exec_binprm fs/exec.c:1680 [inline]
       do_execveat_common.isra.0+0xf32/0x1c70 fs/exec.c:1802
       do_execveat fs/exec.c:1858 [inline]
       SYSC_execveat fs/exec.c:1939 [inline]
       SyS_execveat+0x49/0x60 fs/exec.c:1931
       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_syscall+0x81/0x1f0 fs/proc/base.c:639
       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#4 --> &p->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&p->lock);
                               lock(sb_writers#4);
                               lock(&p->lock);
  lock(&sig->cred_guard_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor.2/31257:
 #0:  (&p->lock){+.+.}, at: [<ffffffff8192efba>] seq_read+0xba/0x1160 fs/seq_file.c:165

stack backtrace:
CPU: 0 PID: 31257 Comm: syz-executor.2 Not tainted 4.14.174-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_syscall+0x81/0x1f0 fs/proc/base.c:639
 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: 0033:0x45c849
RSP: 002b:00007febcb60fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007febcb6106d4 RCX: 000000000045c849
RDX: 0000000000000375 RSI: 00000000200017c0 RDI: 0000000000000006
RBP: 000000000076c0e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000085a R14: 00000000004cb1ac R15: 000000000076c0ec
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 0 PID: 31260 Comm: syz-executor.4 Not tainted 4.14.174-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
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0x10a/0x14b lib/fault-inject.c:149
 should_failslab+0xd6/0x130 mm/failslab.c:32
 slab_pre_alloc_hook mm/slab.h:421 [inline]
 slab_alloc_node mm/slab.c:3297 [inline]
 kmem_cache_alloc_node+0x288/0x7a0 mm/slab.c:3640
 __alloc_skb+0x9a/0x4c0 net/core/skbuff.c:193
 alloc_skb include/linux/skbuff.h:980 [inline]
 alloc_skb_with_frags+0x85/0x4f0 net/core/skbuff.c:5228
 sock_alloc_send_pskb+0x586/0x6d0 net/core/sock.c:2081
 __ip6_append_data.isra.0+0x16c0/0x2940 net/ipv6/ip6_output.c:1419
 ip6_append_data+0x1c3/0x300 net/ipv6/ip6_output.c:1582
 l2tp_ip6_sendmsg+0x8c4/0x14c0 net/l2tp/l2tp_ip6.c:649
 inet_sendmsg+0x116/0x4d0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xc5/0x100 net/socket.c:656
 ___sys_sendmsg+0x349/0x840 net/socket.c:2062
 __sys_sendmmsg+0x129/0x330 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f8d8eb85c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f8d8eb866d4 RCX: 000000000045c849
RDX: 0000000000000002 RSI: 0000000020001640 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: 00000000000008d8 R14: 00000000004cb7b3 R15: 0000000000000000
libceph: connect [d::]:6789 error -101
libceph: mon0 [d::]:6789 connect error
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 0 PID: 31279 Comm: syz-executor.4 Not tainted 4.14.174-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
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0x10a/0x14b lib/fault-inject.c:149
 should_failslab+0xd6/0x130 mm/failslab.c:32
 slab_pre_alloc_hook mm/slab.h:421 [inline]
 slab_alloc_node mm/slab.c:3297 [inline]
 kmem_cache_alloc_node_trace+0x292/0x7b0 mm/slab.c:3659
 __do_kmalloc_node mm/slab.c:3681 [inline]
 __kmalloc_node_track_caller+0x38/0x70 mm/slab.c:3696
 __kmalloc_reserve.isra.0+0x35/0xd0 net/core/skbuff.c:137
 __alloc_skb+0xca/0x4c0 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:980 [inline]
 alloc_skb_with_frags+0x85/0x4f0 net/core/skbuff.c:5228
 sock_alloc_send_pskb+0x586/0x6d0 net/core/sock.c:2081
 __ip6_append_data.isra.0+0x16c0/0x2940 net/ipv6/ip6_output.c:1419
 ip6_append_data+0x1c3/0x300 net/ipv6/ip6_output.c:1582
 l2tp_ip6_sendmsg+0x8c4/0x14c0 net/l2tp/l2tp_ip6.c:649
 inet_sendmsg+0x116/0x4d0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xc5/0x100 net/socket.c:656
 ___sys_sendmsg+0x349/0x840 net/socket.c:2062
 __sys_sendmmsg+0x129/0x330 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f8d8eb85c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f8d8eb866d4 RCX: 000000000045c849
RDX: 0000000000000002 RSI: 0000000020001640 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: 00000000000008d8 R14: 00000000004cb7b3 R15: 0000000000000001
libceph: connect [d::]:6789 error -101
libceph: mon0 [d::]:6789 connect error
libceph: connect [::6]:6789 error -101
libceph: mon1 [::6]:6789 connect error
libceph: connect [::6]:6789 error -101
libceph: mon1 [::6]:6789 connect error
audit: type=1804 audit(1585610011.608:196): pid=31514 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op="invalid_pcr" cause="ToMToU" comm="syz-executor.0" name="/root/syzkaller-testdir417160087/syzkaller.xzic6p/65/file0" dev="sda1" ino=16565 res=1
device lo entered promiscuous mode
Y�4��`Ҙ: renamed from lo
libceph: connect [::6]:6789 error -101
libceph: mon1 [::6]:6789 connect error
libceph: connect [d::]:6789 error -101
libceph: mon0 [d::]:6789 connect error
libceph: connect [d::]:6789 error -101
libceph: mon0 [d::]:6789 connect error
libceph: connect [d::]:6789 error -101
libceph: mon0 [d::]:6789 connect error
md: invalid raid superblock magic on ram0
md: ram0 does not have a valid v0.0 superblock, not importing!
md: md_import_device returned -22
libceph: connect [::6]:6789 error -101
libceph: mon1 [::6]:6789 connect error
md: invalid raid superblock magic on ram0
md: ram0 does not have a valid v0.0 superblock, not importing!
md: md_import_device returned -22
libceph: connect [::6]:6789 error -101
libceph: mon1 [::6]:6789 connect error
jfs: Unrecognized mount option "fowner=00000000000000000000" or missing value