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possible deadlock in vfs_fileattr_set

Status: auto-obsoleted due to no activity on 2023/08/10 15:05
Reported-by: syzbot+4d13b6867728d468649c@syzkaller.appspotmail.com
First crash: 832d, last: 832d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in vfs_fileattr_set (2) origin:lts-only 4 C error 3 28d 167d 0/3 upstream: reported C repro on 2025/02/05 13:53
upstream possible deadlock in vfs_fileattr_set reiserfs 4 C done 10 701d 982d 0/29 auto-obsoleted due to no activity on 2023/11/29 02:28
linux-6.1 possible deadlock in vfs_fileattr_set origin:upstream missing-backport 4 C done 3 198d 482d 0/3 upstream: reported C repro on 2024/03/27 09:48

Sample crash report:
REISERFS (device loop3): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
5.15.106-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/6393 is trying to acquire lock:
ffff00011fce02e0 (&type->i_mutex_dir_key#16){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
ffff00011fce02e0 (&type->i_mutex_dir_key#16){+.+.}-{3:3}, at: vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:685

but task is already holding lock:
ffff0000d789c460 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:421

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#21){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1742 [inline]
       sb_start_write+0xf0/0x3ac include/linux/fs.h:1812
       mnt_want_write_file+0x64/0x1e8 fs/namespace.c:421
       reiserfs_ioctl+0x188/0x4b8 fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&sbi->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364
       __lookup_slow+0x250/0x388 fs/namei.c:1659
       lookup_one_len+0x178/0x28c fs/namei.c:2688
       reiserfs_lookup_privroot+0x8c/0x204 fs/reiserfs/xattr.c:980
       reiserfs_fill_super+0x1494/0x1e8c fs/reiserfs/super.c:2196
       mount_bdev+0x26c/0x368 fs/super.c:1378
       get_super_block+0x44/0x58 fs/reiserfs/super.c:2608
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
       vfs_get_tree+0x90/0x274 fs/super.c:1508
       do_new_mount+0x25c/0x8c8 fs/namespace.c:2994
       path_mount+0x590/0x104c fs/namespace.c:3324
       do_mount fs/namespace.c:3337 [inline]
       __do_sys_mount fs/namespace.c:3545 [inline]
       __se_sys_mount fs/namespace.c:3522 [inline]
       __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3522
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&type->i_mutex_dir_key#16){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3787 [inline]
       __lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
       down_write+0x110/0x260 kernel/locking/rwsem.c:1541
       inode_lock include/linux/fs.h:787 [inline]
       vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:685
       do_vfs_ioctl+0x1634/0x2a38
       __do_sys_ioctl fs/ioctl.c:872 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#16 --> &sbi->lock --> sb_writers#21

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#21);
                               lock(&sbi->lock);
                               lock(sb_writers#21);
  lock(&type->i_mutex_dir_key#16);

 *** DEADLOCK ***

1 lock held by syz-executor.3/6393:
 #0: ffff0000d789c460 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:421

stack backtrace:
CPU: 1 PID: 6393 Comm: syz-executor.3 Not tainted 5.15.106-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3787 [inline]
 __lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
 down_write+0x110/0x260 kernel/locking/rwsem.c:1541
 inode_lock include/linux/fs.h:787 [inline]
 vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:685
 do_vfs_ioctl+0x1634/0x2a38
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:860
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/04/12 15:05 linux-5.15.y d86dfc4d95cd 1a1596b6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in vfs_fileattr_set
* Struck through repros no longer work on HEAD.