[v6.1] possible deadlock in vfs_fileattr_set

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e5cd595e23c1 Linux 6.1.83
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10bca1e6180000
kernel config: https://syzkaller.appspot.com/x/.config?x=638c7154137d2582
dashboard link: https://syzkaller.appspot.com/bug?extid=4c1ea7bac08a9dd127b3
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a9b3de36bd43/disk-e5cd595e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2af9bc6e6ea4/vmlinux-e5cd595e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7f58381bafc0/Image-e5cd595e.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4c1ea7...@syzkaller.appspotmail.com

REISERFS (device loop2): Using tea hash to sort names
REISERFS (device loop2): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.83-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/4346 is trying to acquire lock:
ffff0000f1a802e0 (&type->i_mutex_dir_key#9){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff0000f1a802e0 (&type->i_mutex_dir_key#9){+.+.}-{3:3}, at: vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:681

but task is already holding lock:
ffff0000d1560460 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#14){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1891 [inline]
sb_start_write+0x7c/0x308 include/linux/fs.h:1966
mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437
reiserfs_ioctl+0x184/0x454 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #1 (&sbi->lock){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364
__lookup_slow+0x250/0x374 fs/namei.c:1690
lookup_one_len+0x178/0x28c fs/namei.c:2742
reiserfs_lookup_privroot+0x8c/0x204 fs/reiserfs/xattr.c:973
reiserfs_fill_super+0x1bc0/0x2028 fs/reiserfs/super.c:2174
mount_bdev+0x274/0x370 fs/super.c:1432
get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
legacy_get_tree+0xd4/0x16c fs/fs_context.c:632
vfs_get_tree+0x90/0x274 fs/super.c:1562
do_new_mount+0x278/0x8fc fs/namespace.c:3051
path_mount+0x590/0xe5c fs/namespace.c:3381
do_mount fs/namespace.c:3394 [inline]
__do_sys_mount fs/namespace.c:3602 [inline]
__se_sys_mount fs/namespace.c:3579 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3579
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #0 (&type->i_mutex_dir_key#9){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain kernel/locking/lockdep.c:3825 [inline]
__lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:758 [inline]
vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:681
do_vfs_ioctl+0x14cc/0x26f8
__do_sys_ioctl fs/ioctl.c:868 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

other info that might help us debug this:

Chain exists of:
&type->i_mutex_dir_key#9 --> &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#9);

*** DEADLOCK ***

1 lock held by syz-executor.2/4346:
#0: ffff0000d1560460 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437

stack backtrace:
CPU: 0 PID: 4346 Comm: syz-executor.2 Not tainted 6.1.83-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x5c lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2048
check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3825 [inline]
__lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:758 [inline]
vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:681
do_vfs_ioctl+0x14cc/0x26f8
__do_sys_ioctl fs/ioctl.c:868 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: e5cd595e23c1 Linux 6.1.83
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=137de879180000

kernel config: https://syzkaller.appspot.com/x/.config?x=638c7154137d2582
dashboard link: https://syzkaller.appspot.com/bug?extid=4c1ea7bac08a9dd127b3
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1297fb6e180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1167a265180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a9b3de36bd43/disk-e5cd595e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2af9bc6e6ea4/vmlinux-e5cd595e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7f58381bafc0/Image-e5cd595e.gz.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/c5e00b08e872/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4c1ea7...@syzkaller.appspotmail.com

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
6.1.83-syzkaller #0 Not tainted
------------------------------------------------------

syz-executor250/4221 is trying to acquire lock:
ffff0000e20702e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff0000e20702e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:681

but task is already holding lock:

ffff0000de082460 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#8){.+.+}-{0:0}:

-> #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 kernel/locking/lockdep.c:3825 [inline]
__lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:758 [inline]
vfs_fileattr_set+0x110/0xad4 fs/ioctl.c:681
do_vfs_ioctl+0x14cc/0x26f8
__do_sys_ioctl fs/ioctl.c:868 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

other info that might help us debug this:

Chain exists of:

&type->i_mutex_dir_key#6 --> &sbi->lock --> sb_writers#8

Possible unsafe locking scenario:

CPU0 CPU1
---- ----

lock(sb_writers#8);
lock(&sbi->lock);
lock(sb_writers#8);
lock(&type->i_mutex_dir_key#6);

*** DEADLOCK ***

1 lock held by syz-executor250/4221:
#0: ffff0000de082460 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437

stack backtrace:
CPU: 0 PID: 4221 Comm: syz-executor250 Not tainted 6.1.83-syzkaller #0

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.