syzbot


possible deadlock in vfs_setxattr

Status: upstream: reported C repro on 2023/08/23 04:15
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+a235608874608e7103c3@syzkaller.appspotmail.com
First crash: 306d, last: 23d
Bug presence (1)
Date Name Commit Repro Result
2024/02/27 upstream (ToT) 45ec2f5f6ed3 C [report] possible deadlock in vfs_setxattr
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in vfs_setxattr (2) reiserfs C inconclusive done 16 151d 391d 0/27 auto-obsoleted due to no activity on 2024/05/04 21:03
linux-5.15 possible deadlock in vfs_setxattr origin:upstream C 9 28d 120d 0/3 upstream: reported C repro on 2024/02/25 17:13
upstream possible deadlock in vfs_setxattr reiserfs 2 526d 541d 0/27 auto-obsoleted due to no activity on 2023/05/15 07:15
Fix bisection attempts (7)
Created Duration User Patch Repo Result
2024/06/01 13:57 58m bisect fix linux-6.1.y job log (0) log
2024/03/28 17:56 2h17m bisect fix linux-6.1.y job log (0) log
2024/02/22 21:04 1h25m bisect fix linux-6.1.y job log (0) log
2024/01/13 09:03 1h45m bisect fix linux-6.1.y job log (0) log
2023/12/13 23:32 1h45m bisect fix linux-6.1.y job log (0) log
2023/11/13 21:00 1h27m bisect fix linux-6.1.y job log (0) log
2023/10/11 04:58 1h24m bisect fix linux-6.1.y job log (0) log

Sample crash report:
REISERFS (device loop0): journal params: device loop0, size 512, journal first block 18, max trans len 256, max batch 225, max commit age 30, max trans age 30
REISERFS (device loop0): checking transaction log (loop0)
REISERFS (device loop0): Using tea hash to sort names
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.79-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor182/3544 is trying to acquire lock:
ffff8880735282e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff8880735282e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: vfs_setxattr+0x1dd/0x420 fs/xattr.c:308

but task is already holding lock:
ffff888023684460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#9){.+.+}-{0:0}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1875 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs.h:1950
       mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
       reiserfs_ioctl+0x170/0x340 fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&sbi->lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x15c/0x4b0 fs/reiserfs/namei.c:364
       __lookup_slow+0x27e/0x3d0 fs/namei.c:1690
       lookup_one_len+0x187/0x2d0 fs/namei.c:2742
       reiserfs_lookup_privroot+0x85/0x1e0 fs/reiserfs/xattr.c:973
       reiserfs_fill_super+0x21bd/0x2620 fs/reiserfs/super.c:2174
       mount_bdev+0x2c9/0x3f0 fs/super.c:1432
       legacy_get_tree+0xeb/0x180 fs/fs_context.c:632
       vfs_get_tree+0x88/0x270 fs/super.c:1562
       do_new_mount+0x2ba/0xb40 fs/namespace.c:3051
       do_mount fs/namespace.c:3394 [inline]
       __do_sys_mount fs/namespace.c:3602 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3579
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:756 [inline]
       vfs_setxattr+0x1dd/0x420 fs/xattr.c:308
       do_setxattr fs/xattr.c:594 [inline]
       setxattr+0x250/0x2b0 fs/xattr.c:617
       path_setxattr+0x1bc/0x2a0 fs/xattr.c:636
       __do_sys_setxattr fs/xattr.c:652 [inline]
       __se_sys_setxattr fs/xattr.c:648 [inline]
       __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:648
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#6 --> &sbi->lock --> sb_writers#9

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#9);
                               lock(&sbi->lock);
                               lock(sb_writers#9);
  lock(&type->i_mutex_dir_key#6);

 *** DEADLOCK ***

1 lock held by syz-executor182/3544:
 #0: ffff888023684460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393

stack backtrace:
CPU: 1 PID: 3544 Comm: syz-executor182 Not tainted 6.1.79-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 down_write+0x36/0x60 kernel/locking/rwsem.c:1573
 inode_lock include/linux/fs.h:756 [inline]
 vfs_setxattr+0x1dd/0x420 fs/xattr.c:308
 do_setxattr fs/xattr.c:594 [inline]
 setxattr+0x250/0x2b0 fs/xattr.c:617
 path_setxattr+0x1bc/0x2a0 fs/xattr.c:636
 __do_sys_setxattr fs/xattr.c:652 [inline]
 __se_sys_setxattr fs/xattr.c:648 [inline]
 __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:648
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f983571e649
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff56dd08e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007fff56dd0a

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/02/27 16:05 linux-6.1.y 81e1dc2f7001 05e69c83 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan possible deadlock in vfs_setxattr
2023/08/23 04:14 linux-6.1.y 6c44e13dc284 b81ca3f6 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 possible deadlock in vfs_setxattr
2024/04/29 11:09 linux-6.1.y f2295faba5e8 27e33c58 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in vfs_setxattr
2024/04/24 18:04 linux-6.1.y 6741e066ec76 8bdc0f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in vfs_setxattr
2024/04/04 11:22 linux-6.1.y 347385861c50 0ee3535e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in vfs_setxattr
* Struck through repros no longer work on HEAD.