[v6.1] possible deadlock in path_openat

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syzbot

unread,

Mar 13, 2023, 12:18:54 PM3/13/23

to syzkaller...@googlegroups.com

Hello,

syzbot found the following issue on:

HEAD commit: 6449a0ba6843 Linux 6.1.19
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16f8e0a4c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=75eadb21ef1208e4
dashboard link: https://syzkaller.appspot.com/bug?extid=5065469deff7539fdec3
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/dc227ecd3e21/disk-6449a0ba.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d08e21b50c2/vmlinux-6449a0ba.xz
kernel image: https://storage.googleapis.com/syzbot-assets/71a43f2c4d2c/Image-6449a0ba.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+506546...@syzkaller.appspotmail.com

REISERFS (device loop5): using 3.5.x disk format
REISERFS (device loop5): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.19-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/14936 is trying to acquire lock:
ffff000114e1ece0 (&type->i_mutex_dir_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff000114e1ece0 (&type->i_mutex_dir_key#9){++++}-{3:3}, at: open_last_lookups fs/namei.c:3478 [inline]
ffff000114e1ece0 (&type->i_mutex_dir_key#9){++++}-{3:3}, at: path_openat+0x5ec/0x2548 fs/namei.c:3711

but task is already holding lock:
ffff000112acc460 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#17){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1832 [inline]
sb_start_write+0x7c/0x308 include/linux/fs.h:1907
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:581

-> #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:1685
lookup_one_len+0x178/0x28c fs/namei.c:2711
reiserfs_lookup_privroot+0x8c/0x204 fs/reiserfs/xattr.c:973
reiserfs_fill_super+0x15b4/0x2028 fs/reiserfs/super.c:2192
mount_bdev+0x26c/0x368 fs/super.c:1414
get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
vfs_get_tree+0x90/0x274 fs/super.c:1544
do_new_mount+0x25c/0x8c8 fs/namespace.c:3040
path_mount+0x590/0xe58 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3568
__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:581

-> #0 (&type->i_mutex_dir_key#9){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x300/0x8e4 kernel/locking/lockdep.c:5669
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:756 [inline]
open_last_lookups fs/namei.c:3478 [inline]
path_openat+0x5ec/0x2548 fs/namei.c:3711
do_filp_open+0x1bc/0x3cc fs/namei.c:3741
do_sys_openat2+0x128/0x3d8 fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_openat fs/open.c:1342 [inline]
__se_sys_openat fs/open.c:1337 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1337
__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:581

other info that might help us debug this:

Chain exists of:
&type->i_mutex_dir_key#9 --> &sbi->lock --> sb_writers#17

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_writers#17);
lock(&sbi->lock);
lock(sb_writers#17);
lock(&type->i_mutex_dir_key#9);

*** DEADLOCK ***

1 lock held by syz-executor.5/14936:
#0: ffff000112acc460 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393

stack backtrace:
CPU: 1 PID: 14936 Comm: syz-executor.5 Not tainted 6.1.19-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
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:2056
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x300/0x8e4 kernel/locking/lockdep.c:5669
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:756 [inline]
open_last_lookups fs/namei.c:3478 [inline]
path_openat+0x5ec/0x2548 fs/namei.c:3711
do_filp_open+0x1bc/0x3cc fs/namei.c:3741
do_sys_openat2+0x128/0x3d8 fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_openat fs/open.c:1342 [inline]
__se_sys_openat fs/open.c:1337 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1337
__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:581

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

syzbot

unread,

Mar 17, 2023, 9:15:50 AM3/17/23

to syzkaller...@googlegroups.com

Hello,

syzbot found the following issue on:

HEAD commit: 8020ae3c051d Linux 5.15.103
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11b93734c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f95b212e0ccdd4d1
dashboard link: https://syzkaller.appspot.com/bug?extid=2c421a1aee9406682e5d

compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:

disk image: https://storage.googleapis.com/syzbot-assets/6153dfa8dcc0/disk-8020ae3c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2093d52db59f/vmlinux-8020ae3c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/85041d0bd356/Image-8020ae3c.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+2c421a...@syzkaller.appspotmail.com

REISERFS warning (device loop2): jdm-13090 reiserfs_new_inode: ACLs aren't enabled in the fs, but vfs thinks they are!
REISERFS (device loop2): Created .reiserfs_priv - reserved for xattr storage.

======================================================
WARNING: possible circular locking dependency detected

5.15.103-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/6657 is trying to acquire lock:
ffff0000df6f8980 (&type->i_mutex_dir_key#14){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
ffff0000df6f8980 (&type->i_mutex_dir_key#14){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3459 [inline]
ffff0000df6f8980 (&type->i_mutex_dir_key#14){+.+.}-{3:3}, at: path_openat+0x63c/0x26f0 fs/namei.c:3669

but task is already holding lock:

ffff0000d71e2460 (sb_writers#24){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#24){.+.+}-{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:1369
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:1499
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#14){+.+.}-{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+0x2c0/0x89c kernel/locking/lockdep.c:5622
down_write+0x110/0x260 kernel/locking/rwsem.c:1541
inode_lock include/linux/fs.h:787 [inline]
open_last_lookups fs/namei.c:3459 [inline]
path_openat+0x63c/0x26f0 fs/namei.c:3669
do_filp_open+0x1a8/0x3b4 fs/namei.c:3699
do_sys_openat2+0x128/0x3d8 fs/open.c:1211
do_sys_open fs/open.c:1227 [inline]
__do_sys_openat fs/open.c:1243 [inline]
__se_sys_openat fs/open.c:1238 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1238
__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#14 --> &sbi->lock --> sb_writers#24

Possible unsafe locking scenario:

CPU0 CPU1
---- ----

lock(sb_writers#24);
lock(&sbi->lock);
lock(sb_writers#24);
lock(&type->i_mutex_dir_key#14);

*** DEADLOCK ***

1 lock held by syz-executor.2/6657:
#0: ffff0000d71e2460 (sb_writers#24){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

stack backtrace:
CPU: 1 PID: 6657 Comm: syz-executor.2 Not tainted 5.15.103-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+0x2c0/0x89c kernel/locking/lockdep.c:5622
down_write+0x110/0x260 kernel/locking/rwsem.c:1541
inode_lock include/linux/fs.h:787 [inline]
open_last_lookups fs/namei.c:3459 [inline]
path_openat+0x63c/0x26f0 fs/namei.c:3669
do_filp_open+0x1a8/0x3b4 fs/namei.c:3699
do_sys_openat2+0x128/0x3d8 fs/open.c:1211
do_sys_open fs/open.c:1227 [inline]
__do_sys_openat fs/open.c:1243 [inline]
__se_sys_openat fs/open.c:1238 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1238
__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

syzbot

unread,

May 16, 2023, 9:22:59 AM5/16/23

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: b0ece631f84a Linux 5.15.111
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11250a7e280000
kernel config: https://syzkaller.appspot.com/x/.config?x=db3750b003ff805e

dashboard link: https://syzkaller.appspot.com/bug?extid=2c421a1aee9406682e5d
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14e396d6280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d09631280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eded75b6c3f9/disk-b0ece631.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/20e5ae802010/vmlinux-b0ece631.xz
kernel image: https://storage.googleapis.com/syzbot-assets/05d665c869f3/Image-b0ece631.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/a86924609a75/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2c421a...@syzkaller.appspotmail.com

reiserfs: enabling write barrier flush mode
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.

======================================================
WARNING: possible circular locking dependency detected

5.15.111-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor105/3962 is trying to acquire lock:
ffff0000dc7e02e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
ffff0000dc7e02e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3459 [inline]
ffff0000dc7e02e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: path_openat+0x63c/0x26f0 fs/namei.c:3669

but task is already holding lock:

ffff0000c2dea460 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

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

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#6){+.+.}-{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]
open_last_lookups fs/namei.c:3459 [inline]
path_openat+0x63c/0x26f0 fs/namei.c:3669
do_filp_open+0x1a8/0x3b4 fs/namei.c:3699
do_sys_openat2+0x128/0x3d8 fs/open.c:1211
do_sys_open fs/open.c:1227 [inline]
__do_sys_openat fs/open.c:1243 [inline]
__se_sys_openat fs/open.c:1238 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1238
__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#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-executor105/3962:
#0: ffff0000c2dea460 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377

stack backtrace:
CPU: 1 PID: 3962 Comm: syz-executor105 Not tainted 5.15.111-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023

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

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.

syzbot

unread,

Jun 18, 2023, 1:21:01 PM6/18/23

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: ca87e77a2ef8 Linux 6.1.34
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14bd2aa7280000
kernel config: https://syzkaller.appspot.com/x/.config?x=c188e92022a334b

dashboard link: https://syzkaller.appspot.com/bug?extid=5065469deff7539fdec3
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a40d87280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1663cbcf280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f48d514c343c/disk-ca87e77a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/563336f1f216/vmlinux-ca87e77a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2254afa3642b/bzImage-ca87e77a.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4dde25ae2dab/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+506546...@syzkaller.appspotmail.com

reiserfs: enabling write barrier flush mode

REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.

======================================================
WARNING: possible circular locking dependency detected

6.1.34-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor235/3539 is trying to acquire lock:
ffff8880747802e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff8880747802e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3478 [inline]
ffff8880747802e0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}, at: path_openat+0x7b6/0x2e60 fs/namei.c:3711

but task is already holding lock:

ffff88807ce2e460 (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:5669

percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1832 [inline]

sb_start_write+0x4d/0x1c0 include/linux/fs.h:1907
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:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&sbi->lock){+.+.}-{3:3}:

lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
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:1685
lookup_one_len+0x187/0x2d0 fs/namei.c:2711
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:1423
legacy_get_tree+0xeb/0x180 fs/fs_context.c:610
vfs_get_tree+0x88/0x270 fs/super.c:1553
do_new_mount+0x28b/0xae0 fs/namespace.c:3040

do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]

__se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&type->i_mutex_dir_key#6){+.+.}-{3:3}:

check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]

validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573

inode_lock include/linux/fs.h:756 [inline]
open_last_lookups fs/namei.c:3478 [inline]

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-executor235/3539:
#0: ffff88807ce2e460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393

stack backtrace:
CPU: 0 PID: 3539 Comm: syz-executor235 Not tainted 6.1.34-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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:2178

check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]

inode_lock include/linux/fs.h:756 [inline]
open_last_lookups fs/namei.c:3478 [inline]

path_openat+0x7b6/0x2e60 fs/namei.c:3711
do_filp_open+0x230/0x480 fs/namei.c:3741
do_sys_openat2+0x13b/0x500 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_openat fs/open.c:1350 [inline]
__se_sys_openat fs/open.c:1345 [inline]
__x64_sys_openat+0x243/0x290 fs/open.c:1345
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fe639720909
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffedd79f0d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe639720909
RDX: 000000000000275a RSI: 0000000020000280 RDI: 00000000ffffff9c
RBP: 00007fe6396e01a0 R08: 00000000200000c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe6396e0230
R13: 0000000000000000 R14: 0000000000000000

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