syzbot


possible deadlock in vfs_removexattr

Status: upstream: reported on 2024/05/13 04:57
Reported-by: syzbot+3a14550adf50e687c7b5@syzkaller.appspotmail.com
First crash: 32d, last: 32d
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in vfs_removexattr (2) reiserfs 2 144d 144d 0/27 auto-obsoleted due to no activity on 2024/05/01 20:00
linux-5.15 possible deadlock in vfs_removexattr 1 73d 73d 0/3 upstream: reported on 2024/04/03 03:33
upstream possible deadlock in vfs_removexattr reiserfs 1 366d 361d 0/27 auto-obsoleted due to no activity on 2023/09/22 21:50

Sample crash report:
REISERFS (device loop4): checking transaction log (loop4)
REISERFS (device loop4): Using tea hash to sort names
REISERFS (device loop4): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.90-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/6537 is trying to acquire lock:
ffff8880580002e0 (&type->i_mutex_dir_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff8880580002e0 (&type->i_mutex_dir_key#10){+.+.}-{3:3}, at: vfs_removexattr+0xe8/0x2a0 fs/xattr.c:535

but task is already holding lock:
ffff888013aee460 (sb_writers#14){.+.+}-{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#14){.+.+}-{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:1891 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs.h:1966
       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+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #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+0x1957/0x2620 fs/reiserfs/super.c:2192
       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+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&type->i_mutex_dir_key#10){+.+.}-{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:758 [inline]
       vfs_removexattr+0xe8/0x2a0 fs/xattr.c:535
       removexattr fs/xattr.c:878 [inline]
       path_removexattr+0x22a/0x320 fs/xattr.c:892
       __do_sys_removexattr fs/xattr.c:906 [inline]
       __se_sys_removexattr fs/xattr.c:903 [inline]
       __x64_sys_removexattr+0x5c/0x70 fs/xattr.c:903
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#10 --> &sbi->lock --> sb_writers#14

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#14);
                               lock(&sbi->lock);
                               lock(sb_writers#14);
  lock(&type->i_mutex_dir_key#10);

 *** DEADLOCK ***

1 lock held by syz-executor.4/6537:
 #0: ffff888013aee460 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393

stack backtrace:
CPU: 0 PID: 6537 Comm: syz-executor.4 Not tainted 6.1.90-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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:758 [inline]
 vfs_removexattr+0xe8/0x2a0 fs/xattr.c:535
 removexattr fs/xattr.c:878 [inline]
 path_removexattr+0x22a/0x320 fs/xattr.c:892
 __do_sys_removexattr fs/xattr.c:906 [inline]
 __se_sys_removexattr fs/xattr.c:903 [inline]
 __x64_sys_removexattr+0x5c/0x70 fs/xattr.c:903
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f353b87dd69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f353a3f60c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000c5
RAX: ffffffffffffffda RBX: 00007f353b9abf80 RCX: 00007f353b87dd69
RDX: 0000000000000000 RSI: 0000000020000540 RDI: 00000000200000c0
RBP: 00007f353b8ca49e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f353b9abf80 R15: 00007ffd85dfe038
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/13 04:56 linux-6.1.y 909ba1f1b414 9026e142 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in vfs_removexattr
2024/05/13 05:03 linux-6.1.y 909ba1f1b414 9026e142 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in vfs_removexattr
* Struck through repros no longer work on HEAD.