syzbot


possible deadlock in path_openat

Status: auto-obsoleted due to no activity on 2022/09/16 21:43
Reported-by: syzbot+a55ccfc8a853d3cff213@syzkaller.appspotmail.com
First crash: 1527d, last: 972d

Cause bisection: introduced by (bisect log) :
commit 8e54cadab447dae779f80f79c87cbeaea9594f60
Author: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun Nov 27 01:05:42 2016 +0000

  fix default_file_splice_read()

Crash: INFO: possible circular locking dependency detected ] (log)
Repro: C syz .config

Fix bisection: fixed by (bisect log) [merge commit]:
commit 52d2d44eee8091e740d0d275df1311fb8373c9a9
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Wed Jun 19 10:04:55 2019 +0000

  Merge v5.2-rc5 into drm-next

similar bugs (4):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-49 possible deadlock in path_openat 5 1101d 1117d 0/3 auto-closed as invalid on 2020/03/24 08:43
upstream possible deadlock in path_openat (2) C error 4 14h09m 50d 0/24 upstream: reported C repro on 2022/10/11 06:35
linux-4.14 possible deadlock in path_openat C error 324 54d 1316d 0/1 upstream: reported C repro on 2019/04/24 01:40
linux-4.19 possible deadlock in path_openat C 853 11d 1264d 0/1 upstream: reported C repro on 2019/06/15 07:08
Patch testing requests:
Created Duration User Patch Repo Result
2022/09/16 19:29 15m upstream OK log
2022/09/13 05:27 18m upstream OK log
2022/09/12 18:27 15m linux-next OK log

Sample crash report:
overlayfs: workdir and upperdir must reside under the same mount
======================================================
WARNING: possible circular locking dependency detected
5.1.0-rc5+ #74 Not tainted
------------------------------------------------------
syz-executor949/9348 is trying to acquire lock:
000000005d993096 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: inode_lock_shared include/linux/fs.h:782 [inline]
000000005d993096 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: do_last fs/namei.c:3321 [inline]
000000005d993096 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: path_openat+0x1e98/0x46e0 fs/namei.c:3533

but task is already holding lock:
00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline]
00000000ef248b1d (&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:

-> #4 (&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_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102
       do_io_accounting+0x1f4/0x830 fs/proc/base.c:2740
       proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2789
       proc_single_show+0xf6/0x170 fs/proc/base.c:744
       seq_read+0x4db/0x1130 fs/seq_file.c:229
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_loop_readv_writev fs/read_write.c:688 [inline]
       do_iter_read+0x4a9/0x660 fs/read_write.c:922
       vfs_readv+0xf0/0x160 fs/read_write.c:984
       kernel_readv fs/splice.c:358 [inline]
       default_file_splice_read+0x475/0x890 fs/splice.c:413
       do_splice_to+0x12a/0x190 fs/splice.c:876
       splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953
       do_splice_direct+0x1da/0x2a0 fs/splice.c:1062
       do_sendfile+0x597/0xd00 fs/read_write.c:1443
       __do_sys_sendfile64 fs/read_write.c:1504 [inline]
       __se_sys_sendfile64 fs/read_write.c:1490 [inline]
       __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490
       do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #3 (&p->lock){+.+.}:
       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
       seq_read+0x71/0x1130 fs/seq_file.c:161
       proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:227
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_loop_readv_writev fs/read_write.c:688 [inline]
       do_iter_read+0x4a9/0x660 fs/read_write.c:922
       vfs_readv+0xf0/0x160 fs/read_write.c:984
       kernel_readv fs/splice.c:358 [inline]
       default_file_splice_read+0x475/0x890 fs/splice.c:413
       do_splice_to+0x12a/0x190 fs/splice.c:876
       do_splice+0x110b/0x1420 fs/splice.c:1183
       __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

-> #2 (&pipe->mutex/1){+.+.}:
       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_nested fs/pipe.c:62 [inline]
       pipe_lock+0x6e/0x80 fs/pipe.c:70
       iter_file_splice_write+0x18b/0xbe0 fs/splice.c:696
       do_splice_from fs/splice.c:847 [inline]
       do_splice+0x70a/0x1420 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

-> #1 (sb_writers#6){.+.+}:
       lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
       percpu_down_read include/linux/percpu-rwsem.h:36 [inline]
       __sb_start_write+0x20b/0x360 fs/super.c:1613
       sb_start_write include/linux/fs.h:1621 [inline]
       mnt_want_write+0x3f/0xc0 fs/namespace.c:358
       ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24
       ovl_do_remove+0xe9/0xd70 fs/overlayfs/dir.c:840
       ovl_rmdir+0x1b/0x20 fs/overlayfs/dir.c:890
       vfs_rmdir fs/namei.c:3878 [inline]
       vfs_rmdir+0x19c/0x470 fs/namei.c:3857
       do_rmdir+0x39e/0x420 fs/namei.c:3939
       __do_sys_rmdir fs/namei.c:3957 [inline]
       __se_sys_rmdir fs/namei.c:3955 [inline]
       __x64_sys_rmdir+0x36/0x40 fs/namei.c:3955
       do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}:
       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
       down_read+0x3b/0x90 kernel/locking/rwsem.c:24
       inode_lock_shared include/linux/fs.h:782 [inline]
       do_last fs/namei.c:3321 [inline]
       path_openat+0x1e98/0x46e0 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:

Chain exists of:
  &ovl_i_mutex_dir_key[depth]#2 --> &p->lock --> &sig->cred_guard_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sig->cred_guard_mutex);
                               lock(&p->lock);
                               lock(&sig->cred_guard_mutex);
  lock(&ovl_i_mutex_dir_key[depth]#2);

 *** DEADLOCK ***

1 lock held by syz-executor949/9348:
 #0: 00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline]
 #0: 00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750

stack backtrace:
CPU: 1 PID: 9348 Comm: syz-executor949 Not tainted 5.1.0-rc5+ #74
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
 down_read+0x3b/0x90 kernel/locking/rwsem.c:24
 inode_lock_shared include/linux/fs.h:782 [inline]
 do_last fs/namei.c:3321 [inline]
 path_openat+0x1e98/0x46e0 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: 0033:0x447169
Code: e8 4c bb 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 bb 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe4c6a6bdb8 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 00000000006dcc68 RCX: 0000000000447169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000000
RBP: 00000000006dcc60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc6c
R13: 00007ffd5a5cb62f R14: 00007fe4c6a6c9c0 R15: 0000000000000000

Crashes (349):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2019/04/19 05:30 upstream 6d906f998179 b0e8efcb .config log report syz C
ci-upstream-kasan-gce-root 2019/04/19 06:25 upstream 6d906f998179 b0e8efcb .config log report syz
ci-upstream-linux-next-kasan-gce-root 2019/04/19 05:24 linux-next 3f018f4a019a b0e8efcb .config log report syz
ci-upstream-kasan-gce-root 2020/04/02 06:08 upstream 919dce24701f a34e2c33 .config log report
ci-upstream-kasan-gce-smack-root 2020/04/01 16:06 upstream 1a323ea5356e a34e2c33 .config log report
ci-upstream-kasan-gce-root 2020/03/30 09:59 upstream 7111951b8d49 05736b29 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/30 08:07 upstream 7111951b8d49 05736b29 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/29 17:38 upstream e595dd94515e 05736b29 .config log report
ci-upstream-kasan-gce-root 2020/03/29 11:17 upstream 906c40438bb6 05736b29 .config log report
ci-upstream-kasan-gce-selinux-root 2020/03/29 09:51 upstream 906c40438bb6 05736b29 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/28 15:52 upstream 69c5eea3128e f1ebdfba .config log report
ci-upstream-kasan-gce-root 2020/03/28 08:44 upstream 69c5eea3128e 831e9a81 .config log report
ci-upstream-kasan-gce-root 2020/03/27 06:35 upstream f3e69428b5e2 7d95711b .config log report
ci-upstream-kasan-gce-smack-root 2020/03/26 21:19 upstream 9420e8ade435 6d25c5a0 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/26 15:57 upstream 1b649e0bcae7 6d25c5a0 .config log report
ci-upstream-kasan-gce-root 2020/03/25 13:33 upstream 76ccd234269b 41f049cc .config log report
ci-upstream-kasan-gce-smack-root 2020/03/24 17:27 upstream 979e52ca0469 68660b21 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/23 17:35 upstream 16fbf79b0f83 84f999d6 .config log report
ci-upstream-kasan-gce-root 2020/03/23 00:45 upstream 67d584e33e54 78267cec .config log report
ci-upstream-kasan-gce-root 2020/03/19 20:17 upstream cd607737f3b8 2c31c529 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/19 18:28 upstream cd607737f3b8 2c31c529 .config log report
ci-upstream-kasan-gce-root 2020/03/18 16:52 upstream ac309e7744be 0a96a13c .config log report
ci-upstream-kasan-gce-root 2020/03/18 01:26 upstream ac309e7744be 97bc55ce .config log report
ci-upstream-kasan-gce-smack-root 2020/03/17 22:49 upstream ac309e7744be 97bc55ce .config log report
ci-upstream-kasan-gce-smack-root 2020/03/15 23:58 upstream a42a7bb6f536 749688d2 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/15 22:32 upstream a42a7bb6f536 749688d2 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/14 18:10 upstream 69a4d0baeeb1 749688d2 .config log report
ci-upstream-kasan-gce-root 2020/03/14 16:13 upstream fffb08b37df9 749688d2 .config log report
ci-upstream-kasan-gce-root 2020/03/09 12:57 upstream 2c523b344dfa 2e9971bb .config log report
ci-upstream-kasan-gce-smack-root 2020/03/09 09:53 upstream 2c523b344dfa 2e9971bb .config log report
ci-upstream-kasan-gce-root 2020/03/09 00:11 upstream 61a09258f2e5 2e9971bb .config log report
ci-upstream-kasan-gce-selinux-root 2020/03/08 16:33 upstream c20037652700 2e9971bb .config log report
ci-upstream-kasan-gce-root 2020/03/02 02:17 upstream 63623fd44972 c88c7b75 .config log report
ci-upstream-kasan-gce-root 2020/02/28 01:59 upstream f8788d86ab28 59b57593 .config log report
ci-upstream-kasan-gce-root 2020/02/27 08:19 upstream f8788d86ab28 59b57593 .config log report
ci-upstream-kasan-gce-selinux-root 2020/02/26 17:47 upstream f8788d86ab28 59b57593 .config log report
ci-upstream-kasan-gce-selinux-root 2020/02/18 06:02 upstream 11a48a5a18c6 1ce142dc .config log report
ci-upstream-kasan-gce-root 2020/02/17 21:18 upstream 11a48a5a18c6 2b411596 .config log report
ci-upstream-kasan-gce-root 2020/02/16 23:49 upstream 11a48a5a18c6 1f448cd6 .config log report
ci-upstream-kasan-gce-root 2020/02/15 21:14 upstream 829e69446995 5d7b90f1 .config log report
ci-upstream-kasan-gce-selinux-root 2020/02/14 10:43 upstream b19e8c684703 5d7b90f1 .config log report
ci-qemu-upstream 2019/12/04 06:36 upstream 63de37476ebd 0ecb9746 .config log report
ci-upstream-kasan-gce-root 2018/09/25 17:17 upstream 2dd68cc7fd8c 0e7547d7 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/04/02 15:25 linux-next 770fbb32d34e a34e2c33 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/03/21 14:21 linux-next 770fbb32d34e 4288d95e .config log report
ci-upstream-linux-next-kasan-gce-root 2020/03/02 21:03 linux-next c99b17ac0399 c88c7b75 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/29 13:37 linux-next bdc5461b23ca 59b57593 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/29 01:39 linux-next bdc5461b23ca 59b57593 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/27 09:49 linux-next bdc5461b23ca 59b57593 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/24 09:38 linux-next bdc5461b23ca d801cb02 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/24 02:01 linux-next bee46b309a13 d801cb02 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/21 05:01 linux-next bee46b309a13 bd2a74a3 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/20 21:22 linux-next f4aba10148cd bd2a74a3 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/18 01:30 linux-next c25a951c50dc 1ce142dc .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/17 07:25 linux-next c25a951c50dc 1f448cd6 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/13 16:55 linux-next 51d5d207918d c5ed587f .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/12 15:19 linux-next 129759899765 84f4fc8a .config log report
* Struck through repros no longer work on HEAD.