syzbot


possible deadlock in seq_read_iter (4)

Status: closed as dup on 2024/05/27 09:33
Subsystems: overlayfs
[Documentation on labels]
Reported-by: syzbot+fcdd1f09adf0e00f70b1@syzkaller.appspotmail.com
First crash: 262d, last: 18d
Duplicate of
Title Repro Cause bisect Fix bisect Count Last Reported
possible deadlock in kernfs_seq_start kernfs C done 15 22d 288d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [overlayfs?] possible deadlock in seq_read_iter (4) 1 (2) 2024/05/27 09:33
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in seq_read_iter 43 17d 288d 0/3 upstream: reported on 2024/04/28 04:21
upstream possible deadlock in seq_read_iter (2) overlayfs C done done 14 412d 571d 25/28 fixed on 2024/02/02 10:05
upstream possible deadlock in seq_read_iter fs 2 1283d 1289d 0/28 auto-closed as invalid on 2021/12/05 03:01
upstream possible deadlock in seq_read_iter (3) overlayfs 148 274d 363d 25/28 fixed on 2024/05/23 00:16

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-syzkaller-01005-gb9d8a295ed6b #0 Not tainted
------------------------------------------------------
syz.9.10415/10238 is trying to acquire lock:
ffff888031389c30 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xd8/0x12b0 fs/seq_file.c:182

but task is already holding lock:
ffff888047c97c68 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock fs/pipe.c:92 [inline]
ffff888047c97c68 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock+0x64/0x80 fs/pipe.c:89

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&pipe->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       pipe_lock fs/pipe.c:92 [inline]
       pipe_lock+0x64/0x80 fs/pipe.c:89
       iter_file_splice_write+0x1eb/0x10b0 fs/splice.c:687
       do_splice_from fs/splice.c:941 [inline]
       do_splice+0x145c/0x1f60 fs/splice.c:1354
       __do_splice+0x327/0x360 fs/splice.c:1436
       __do_sys_splice fs/splice.c:1639 [inline]
       __se_sys_splice fs/splice.c:1621 [inline]
       __x64_sys_splice+0x187/0x250 fs/splice.c:1621
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (sb_writers#6){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1739 [inline]
       sb_start_write include/linux/fs.h:1875 [inline]
       mnt_want_write+0x6f/0x450 fs/namespace.c:547
       ovl_create_object+0x12e/0x300 fs/overlayfs/dir.c:656
       lookup_open.isra.0+0x11c8/0x1580 fs/namei.c:3649
       open_last_lookups fs/namei.c:3748 [inline]
       path_openat+0x904/0x2d70 fs/namei.c:3984
       do_filp_open+0x20c/0x470 fs/namei.c:4014
       do_sys_openat2+0x17a/0x1e0 fs/open.c:1395
       do_sys_open fs/open.c:1410 [inline]
       __do_sys_open fs/open.c:1418 [inline]
       __se_sys_open fs/open.c:1414 [inline]
       __x64_sys_open+0x154/0x1e0 fs/open.c:1414
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}:
       down_read+0x9a/0x330 kernel/locking/rwsem.c:1524
       inode_lock_shared include/linux/fs.h:842 [inline]
       lookup_slow fs/namei.c:1807 [inline]
       walk_component+0x342/0x5b0 fs/namei.c:2112
       lookup_last fs/namei.c:2610 [inline]
       path_lookupat+0x17f/0x770 fs/namei.c:2634
       filename_lookup+0x221/0x5f0 fs/namei.c:2663
       kern_path+0x35/0x50 fs/namei.c:2771
       lookup_bdev+0xd9/0x280 block/bdev.c:1163
       resume_store+0x1d8/0x460 kernel/power/hibernate.c:1242
       kobj_attr_store+0x55/0x80 lib/kobject.c:840
       sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
       kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
       new_sync_write fs/read_write.c:586 [inline]
       vfs_write+0x5ae/0x1150 fs/read_write.c:679
       ksys_write+0x12b/0x250 fs/read_write.c:731
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&of->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
       traverse.part.0.constprop.0+0xac/0x640 fs/seq_file.c:106
       traverse fs/seq_file.c:98 [inline]
       seq_read_iter+0x934/0x12b0 fs/seq_file.c:195
       kernfs_fop_read_iter+0x414/0x580 fs/kernfs/file.c:279
       copy_splice_read+0x620/0xb90 fs/splice.c:365
       do_splice_read fs/splice.c:985 [inline]
       do_splice_read+0x282/0x370 fs/splice.c:959
       splice_direct_to_actor+0x2a4/0xa40 fs/splice.c:1089
       do_splice_direct_actor fs/splice.c:1207 [inline]
       do_splice_direct+0x178/0x250 fs/splice.c:1233
       vfs_copy_file_range+0x5d3/0x15b0 fs/read_write.c:1620
       __do_sys_copy_file_range+0x1a2/0x450 fs/read_write.c:1670
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&p->lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       seq_read_iter+0xd8/0x12b0 fs/seq_file.c:182
       kernfs_fop_read_iter+0x414/0x580 fs/kernfs/file.c:279
       copy_splice_read+0x620/0xb90 fs/splice.c:365
       do_splice_read fs/splice.c:985 [inline]
       do_splice_read+0x282/0x370 fs/splice.c:959
       splice_file_to_pipe+0x109/0x120 fs/splice.c:1295
       do_splice+0x1174/0x1f60 fs/splice.c:1379
       __do_splice+0x159/0x360 fs/splice.c:1436
       __do_sys_splice fs/splice.c:1639 [inline]
       __se_sys_splice fs/splice.c:1621 [inline]
       __x64_sys_splice+0x187/0x250 fs/splice.c:1621
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &p->lock --> sb_writers#6 --> &pipe->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pipe->mutex);
                               lock(sb_writers#6);
                               lock(&pipe->mutex);
  lock(&p->lock);

 *** DEADLOCK ***

1 lock held by syz.9.10415/10238:
 #0: ffff888047c97c68 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock fs/pipe.c:92 [inline]
 #0: ffff888047c97c68 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock+0x64/0x80 fs/pipe.c:89

stack backtrace:
CPU: 0 UID: 0 PID: 10238 Comm: syz.9.10415 Not tainted 6.13.0-syzkaller-01005-gb9d8a295ed6b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
 seq_read_iter+0xd8/0x12b0 fs/seq_file.c:182
 kernfs_fop_read_iter+0x414/0x580 fs/kernfs/file.c:279
 copy_splice_read+0x620/0xb90 fs/splice.c:365
 do_splice_read fs/splice.c:985 [inline]
 do_splice_read+0x282/0x370 fs/splice.c:959
 splice_file_to_pipe+0x109/0x120 fs/splice.c:1295
 do_splice+0x1174/0x1f60 fs/splice.c:1379
 __do_splice+0x159/0x360 fs/splice.c:1436
 __do_sys_splice fs/splice.c:1639 [inline]
 __se_sys_splice fs/splice.c:1621 [inline]
 __x64_sys_splice+0x187/0x250 fs/splice.c:1621
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd647785d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd6455f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007fd647976080 RCX: 00007fd647785d29
RDX: 000000000000000d RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fd647801b08 R08: 0000000000000f3e R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd647976080 R15: 00007fff2cd31458
 </TASK>

Crashes (38):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/22 13:20 upstream b9d8a295ed6b da72ac06 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in seq_read_iter
2024/12/25 11:12 upstream 9b2ffa6148b1 444551c4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in seq_read_iter
2024/11/28 05:25 upstream aaf20f870da0 5df23865 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in seq_read_iter
2024/11/28 05:25 upstream aaf20f870da0 5df23865 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in seq_read_iter
2024/11/28 05:24 upstream aaf20f870da0 5df23865 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in seq_read_iter
2024/11/04 02:28 upstream b9021de3ec2f f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in seq_read_iter
2024/10/25 15:08 upstream ae90f6a6170d c79b8ca5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in seq_read_iter
2024/10/02 15:58 upstream e32cde8d2bd7 02f9582a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/09/10 20:38 upstream 8d8d276ba2fb 86aa7bd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/08/17 02:02 upstream 85652baa895b dbc93b08 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/21 17:23 upstream 50736169ecc8 dac2aa43 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in seq_read_iter
2024/06/17 15:55 upstream 2ccbdf43d5e7 1f11cfd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/17 15:54 upstream 2ccbdf43d5e7 1f11cfd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/09 01:23 upstream 061d1af7b030 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/09 00:02 upstream dc772f8237f9 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/05 17:12 upstream 71d7b52cc33b 5aa1a7c9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/05 10:16 upstream 32f88d65f01b e1e2c66e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/04 11:57 upstream 2ab795141095 11f2afa5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/04 01:06 upstream f06ce441457d a1feae05 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/03 09:45 upstream c3f38fa61af7 0aba2352 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/03 04:19 upstream c3f38fa61af7 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/03 04:18 upstream c3f38fa61af7 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/02 15:05 upstream 83814698cf48 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/02 01:01 upstream 89be4025b0db 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/06/01 12:04 upstream cc8ed4d0a848 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 22:38 upstream d8ec19857b09 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 22:34 upstream d8ec19857b09 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 22:33 upstream d8ec19857b09 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 20:58 upstream d8ec19857b09 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 20:46 upstream d8ec19857b09 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 20:18 upstream d8ec19857b09 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 20:18 upstream d8ec19857b09 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 20:18 upstream d8ec19857b09 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/31 20:18 upstream d8ec19857b09 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/28 19:44 upstream e0cce98fe279 34889ee3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/28 17:31 upstream 2bfcfd584ff5 34889ee3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/27 21:49 upstream 2bfcfd584ff5 761766e6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
2024/05/23 06:43 upstream b6394d6f7159 4d098039 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in seq_read_iter
* Struck through repros no longer work on HEAD.