syzbot


possible deadlock in seq_read (2)

Status: auto-obsoleted due to no activity on 2022/09/24 20:28
Reported-by: syzbot+5378878b09e052edef7f@syzkaller.appspotmail.com
First crash: 1263d, last: 727d

Cause bisection: introduced by (bisect log) [merge commit]:
commit fe38bd6862074c0a2b9be7f31f043aaa70b2af5f
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed Sep 18 16:49:13 2019 +0000

  Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Crash: KASAN: stack-out-of-bounds Read in finish_writeback_work (log)
Repro: C syz .config

Fix bisection: failed (bisect log)
similar bugs (7):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 possible deadlock in seq_read (2) 1 147d 147d 0/1 auto-obsoleted due to no activity on 2022/09/01 16:45
linux-4.14 possible deadlock in seq_read 144 513d 1188d 0/1 auto-closed as invalid on 2021/08/31 02:48
android-44 possible deadlock in seq_read C 632 1029d 1266d 0/2 public: reported C repro on 2019/04/11 08:44
android-49 possible deadlock in seq_read C 56124 1029d 1265d 1/3 public: reported C repro on 2019/04/12 00:00
linux-4.19 possible deadlock in seq_read C error 276 1d02h 1150d 0/1 upstream: reported C repro on 2019/08/05 16:40
upstream possible deadlock in seq_read C 19074 1272d 1762d 13/24 fixed on 2019/04/12 08:05
android-414 possible deadlock in seq_read C 1737 1119d 1266d 0/1 public: reported C repro on 2019/04/11 00:00
Patch testing requests:
Created Duration User Patch Repo Result
2022/09/24 18:30 16m linux-next OK log
2022/09/24 15:30 19m linux-next OK log
2022/09/23 17:30 15m upstream OK log
2022/09/23 14:30 16m upstream OK log
2022/09/21 02:29 15m upstream OK log
2022/09/19 11:29 17m upstream OK log
2022/09/19 06:29 16m upstream OK log

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.5.0-rc2-next-20191220-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor877/11363 is trying to acquire lock:
ffff8880920b8520 (&p->lock){+.+.}, at: seq_read+0x71/0x1170 fs/seq_file.c:161

but task is already holding lock:
ffff8880998ac428 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2880 [inline]
ffff8880998ac428 (sb_writers#3){.+.+}, at: do_sendfile+0x9b9/0xd00 fs/read_write.c:1463

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (sb_writers#3){.+.+}:
       percpu_down_read include/linux/percpu-rwsem.h:40 [inline]
       __sb_start_write+0x241/0x460 fs/super.c:1674
       sb_start_write include/linux/fs.h:1649 [inline]
       mnt_want_write+0x3f/0xc0 fs/namespace.c:354
       ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:21
       ovl_create_object+0xb3/0x2c0 fs/overlayfs/dir.c:596
       ovl_create+0x28/0x30 fs/overlayfs/dir.c:627
       lookup_open+0x12d5/0x1a90 fs/namei.c:3374
       do_last fs/namei.c:3464 [inline]
       path_openat+0xf2a/0x34d0 fs/namei.c:3670
       do_filp_open+0x192/0x260 fs/namei.c:3700
       do_sys_openat2+0x633/0x840 fs/open.c:1152
       do_sys_open+0xfc/0x190 fs/open.c:1168
       ksys_open include/linux/syscalls.h:1385 [inline]
       __do_sys_open fs/open.c:1174 [inline]
       __se_sys_open fs/open.c:1172 [inline]
       __x64_sys_open+0x7e/0xc0 fs/open.c:1172
       do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #2 (&ovl_i_mutex_dir_key[depth]){++++}:
       down_read+0x95/0x440 kernel/locking/rwsem.c:1495
       inode_lock_shared include/linux/fs.h:801 [inline]
       do_last fs/namei.c:3463 [inline]
       path_openat+0x1c60/0x34d0 fs/namei.c:3670
       do_filp_open+0x192/0x260 fs/namei.c:3700
       do_open_execat+0x13b/0x6d0 fs/exec.c:861
       __do_execve_file.isra.0+0x1702/0x22b0 fs/exec.c:1766
       do_execveat_common fs/exec.c:1872 [inline]
       do_execve fs/exec.c:1889 [inline]
       __do_sys_execve fs/exec.c:1965 [inline]
       __se_sys_execve fs/exec.c:1960 [inline]
       __x64_sys_execve+0x8f/0xc0 fs/exec.c:1960
       do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&sig->cred_guard_mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:956 [inline]
       __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
       mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1133
       do_io_accounting+0x1f4/0x820 fs/proc/base.c:2772
       proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2821
       proc_single_show+0xfd/0x1c0 fs/proc/base.c:756
       seq_read+0x4ca/0x1170 fs/seq_file.c:229
       do_loop_readv_writev fs/read_write.c:714 [inline]
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_iter_read+0x4a4/0x660 fs/read_write.c:935
       vfs_readv+0xf0/0x160 fs/read_write.c:997
       kernel_readv fs/splice.c:365 [inline]
       default_file_splice_read+0x4fb/0xa20 fs/splice.c:422
       do_splice_to+0x127/0x180 fs/splice.c:892
       splice_direct_to_actor+0x320/0xa30 fs/splice.c:971
       do_splice_direct+0x1da/0x2a0 fs/splice.c:1080
       do_sendfile+0x597/0xd00 fs/read_write.c:1464
       __do_sys_sendfile64 fs/read_write.c:1525 [inline]
       __se_sys_sendfile64 fs/read_write.c:1511 [inline]
       __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
       do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&p->lock){+.+.}:
       check_prev_add kernel/locking/lockdep.c:2476 [inline]
       check_prevs_add kernel/locking/lockdep.c:2581 [inline]
       validate_chain kernel/locking/lockdep.c:2971 [inline]
       __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
       lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
       __mutex_lock_common kernel/locking/mutex.c:956 [inline]
       __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
       seq_read+0x71/0x1170 fs/seq_file.c:161
       do_loop_readv_writev fs/read_write.c:714 [inline]
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_iter_read+0x4a4/0x660 fs/read_write.c:935
       vfs_readv+0xf0/0x160 fs/read_write.c:997
       kernel_readv fs/splice.c:365 [inline]
       default_file_splice_read+0x4fb/0xa20 fs/splice.c:422
       do_splice_to+0x127/0x180 fs/splice.c:892
       splice_direct_to_actor+0x320/0xa30 fs/splice.c:971
       do_splice_direct+0x1da/0x2a0 fs/splice.c:1080
       do_sendfile+0x597/0xd00 fs/read_write.c:1464
       __do_sys_sendfile64 fs/read_write.c:1525 [inline]
       __se_sys_sendfile64 fs/read_write.c:1511 [inline]
       __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
       do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  &p->lock --> &ovl_i_mutex_dir_key[depth] --> sb_writers#3

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#3);
                               lock(&ovl_i_mutex_dir_key[depth]);
                               lock(sb_writers#3);
  lock(&p->lock);

 *** DEADLOCK ***

1 lock held by syz-executor877/11363:
 #0: ffff8880998ac428 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2880 [inline]
 #0: ffff8880998ac428 (sb_writers#3){.+.+}, at: do_sendfile+0x9b9/0xd00 fs/read_write.c:1463

stack backtrace:
CPU: 0 PID: 11363 Comm: syz-executor877 Not tainted 5.5.0-rc2-next-20191220-syzkaller #0
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+0x197/0x210 lib/dump_stack.c:118
 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685
 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809
 check_prev_add kernel/locking/lockdep.c:2476 [inline]
 check_prevs_add kernel/locking/lockdep.c:2581 [inline]
 validate_chain kernel/locking/lockdep.c:2971 [inline]
 __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
 __mutex_lock_common kernel/locking/mutex.c:956 [inline]
 __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
 seq_read+0x71/0x1170 fs/seq_file.c:161
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_loop_readv_writev fs/read_write.c:701 [inline]
 do_iter_read+0x4a4/0x660 fs/read_write.c:935
 vfs_readv+0xf0/0x160 fs/read_write.c:997
 kernel_readv fs/splice.c:365 [inline]
 default_file_splice_read+0x4fb/0xa20 fs/splice.c:422
 do_splice_to+0x127/0x180 fs/splice.c:892
 splice_direct_to_actor+0x320/0xa30 fs/splice.c:971
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1080
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x448dd9
Code: e8 9c e6 ff ff 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 3b 05 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc37ed06ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000006e4a08 RCX: 0000000000448dd9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00000000006e4a00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000209 R11: 0000000000000246 R12: 00000000006e4a0c
R13: 00007ffecbcb224f R14: 00007fc37ed079c0 R15: 20c49ba5e353f7cf

Crashes (95):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-linux-next-kasan-gce-root 2020/01/02 19:20 linux-next 7ddd09fc4b74 25a0186e .config log report syz C
ci-upstream-kasan-gce-smack-root 2020/05/04 03:24 upstream 262f7a6b8317 58ae5e18 .config log report syz
ci-upstream-kasan-gce-selinux-root 2020/04/29 20:10 upstream 96c9a7802af7 496a08ae .config log report syz
ci-upstream-kasan-gce-smack-root 2020/03/28 18:20 upstream 69c5eea3128e f1ebdfba .config log report syz
ci-upstream-kasan-gce-root 2020/03/12 22:26 upstream e6e6ec48dd0f d850e9d0 .config log report syz
ci-upstream-kasan-gce-root 2020/03/05 01:44 upstream 63623fd44972 c88c7b75 .config log report syz
ci-upstream-linux-next-kasan-gce-root 2020/05/04 08:32 linux-next ac935d227366 58ae5e18 .config log report syz
ci-upstream-kasan-gce-selinux-root 2020/10/01 13:54 upstream 60e720931556 a9767fb2 .config log report info
ci-upstream-kasan-gce-selinux-root 2020/09/09 21:25 upstream 34d4ddd359db 0ea7a887 .config log report
ci-upstream-kasan-gce-root 2020/09/06 20:33 upstream dd9fb9bb3340 abf9ba4f .config log report
ci-upstream-kasan-gce-smack-root 2020/07/31 17:13 upstream d8b9faec54ae d895b3be .config log report
ci-upstream-kasan-gce-smack-root 2020/03/31 02:53 upstream 673b41e04a03 c8d1cc20 .config log report
ci-upstream-kasan-gce-root 2020/03/30 20:09 upstream 7111951b8d49 c8d1cc20 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/29 18:36 upstream e595dd94515e 05736b29 .config log report
ci-upstream-kasan-gce-root 2020/03/29 02:02 upstream 906c40438bb6 05736b29 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/27 17:34 upstream 527630fbf4f1 831e9a81 .config log report
ci-upstream-kasan-gce-smack-root 2020/03/24 06:45 upstream 979e52ca0469 33e14df3 .config log report
ci-upstream-kasan-gce-root 2020/03/20 15:55 upstream 6c90b86a745a 2c31c529 .config log report
ci-upstream-kasan-gce-selinux-root 2020/02/27 21:45 upstream f8788d86ab28 59b57593 .config log report
ci-upstream-kasan-gce-root 2020/02/13 17:42 upstream 0bf999f9c5e7 c5ed587f .config log report
ci-upstream-kasan-gce-smack-root 2020/02/08 10:11 upstream 41dcd67e8868 06150bf1 .config log report
ci-upstream-kasan-gce-smack-root 2020/02/06 14:24 upstream 4c46bef2e96a c91cbc9d .config log report
ci-upstream-kasan-gce-smack-root 2020/02/05 09:48 upstream 6992ca0dd017 93e5e335 .config log report
ci-upstream-kasan-gce-selinux-root 2020/02/04 21:20 upstream 33b40134e5cf 93e5e335 .config log report
ci-upstream-kasan-gce-smack-root 2020/02/01 08:20 upstream 26dca6dbd62d 0eb59c27 .config log report
ci-upstream-kasan-gce-root 2020/01/31 19:48 upstream ccaaaf6fe5a5 c30117b2 .config log report
ci-upstream-kasan-gce-smack-root 2020/01/31 14:48 upstream ccaaaf6fe5a5 5ed23f9a .config log report
ci-upstream-kasan-gce-root 2020/01/30 06:41 upstream 39bed42de2e7 5ed23f9a .config log report
ci-upstream-kasan-gce-root 2020/01/29 12:03 upstream b3a608222336 c8e81ce4 .config log report
ci-upstream-kasan-gce-root 2020/01/28 04:28 upstream d5226fa6dbae 56cd6c9b .config log report
ci-upstream-kasan-gce-root 2020/01/27 14:22 upstream d5226fa6dbae dd56146d .config log report
ci-upstream-kasan-gce-root 2020/01/27 10:26 upstream a45ea48e2bcd dd56146d .config log report
ci-upstream-kasan-gce-selinux-root 2020/01/23 13:37 upstream 131701c697e8 3334d684 .config log report
ci-upstream-kasan-gce-root 2020/01/22 23:43 upstream dbab40bdb42c 3334d684 .config log report
ci-upstream-kasan-gce-smack-root 2020/01/19 15:58 upstream 8f8972a3127f 0342f8c7 .config log report
ci-upstream-kasan-gce-selinux-root 2020/01/18 09:09 upstream 25e73aadf297 3de7aabb .config log report
ci-upstream-kasan-gce-selinux-root 2020/01/16 22:13 upstream f5ae2ea6347a 3de7aabb .config log report
ci-upstream-kasan-gce-selinux-root 2020/01/16 13:11 upstream f5ae2ea6347a 3de7aabb .config log report
ci-upstream-kasan-gce-root 2020/01/16 12:55 upstream f5ae2ea6347a 3de7aabb .config log report
ci-upstream-kasan-gce-selinux-root 2020/01/15 22:45 upstream 51d69817519f f9b69507 .config log report
ci-upstream-kasan-gce-root 2020/01/15 21:30 upstream 51d69817519f f9b69507 .config log report
ci-upstream-kasan-gce-root 2020/01/15 21:20 upstream 51d69817519f f9b69507 .config log report
ci-upstream-kasan-gce-smack-root 2020/01/15 20:34 upstream 51d69817519f f9b69507 .config log report
ci-qemu-upstream 2019/12/02 14:10 upstream 596cf45cbf6e f879db37 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/24 01:08 linux-next bee46b309a13 d801cb02 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/21 19:54 linux-next bee46b309a13 2ffa6679 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/20 06:56 linux-next f4aba10148cd 81230308 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/15 10:12 linux-next 9f01828e9e16 5d7b90f1 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/12 15:41 linux-next 129759899765 84f4fc8a .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/11 15:15 linux-next ac431e2d7b1b 4d1ab643 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/10 02:47 linux-next 2981de746b18 35f5e45e .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/09 09:48 linux-next 6dff1565d69c 6ece2ea5 .config log report
ci-upstream-linux-next-kasan-gce-root 2020/02/08 16:05 linux-next 6dff1565d69c 06150bf1 .config log report
ci-upstream-linux-next-kasan-gce-root 2019/04/14 09:41 linux-next bcb67f0fbce9 c402d8f1 .config log report
* Struck through repros no longer work on HEAD.