[syzbot] possible deadlock in reiserfs_ioctl

syzbot
2022-11-11T18:27:00Z

Hello,

syzbot found the following issue on:

HEAD commit: 0cdb3579f1ee Add linux-next specific files for 20221104
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1608948e880000
kernel config: https://syzkaller.appspot.com/x/.config?x=f8b29628d1d8538b
dashboard link: https://syzkaller.appspot.com/bug?extid=79c303ad05f4041e0dad
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f2b215880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14d3c525880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3d0fa4b872bd/disk-0cdb3579.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/797f855f0497/vmlinux-0cdb3579.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2c5c130d649d/bzImage-0cdb3579.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/41524a2c0287/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+79c303ad05f4041e0dad@syzkaller.appspotmail.com

REISERFS (device loop0): checking transaction log (loop0)
REISERFS (device loop0): Using rupasov hash to sort names
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc3-next-20221104-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor418/5242 is trying to acquire lock:
ffff8880289b2460 (sb_writers#9){.+.+}-{0:0}, at: reiserfs_ioctl+0x19e/0x320 fs/reiserfs/ioctl.c:103

but task is already holding lock:
ffff888016eec090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x75/0xf0 fs/reiserfs/lock.c:27

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&sbi->lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
reiserfs_write_lock+0x75/0xf0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x171/0x490 fs/reiserfs/namei.c:364
__lookup_slow+0x24c/0x460 fs/namei.c:1685
lookup_one_len+0x16a/0x1a0 fs/namei.c:2711
reiserfs_lookup_privroot+0x92/0x280 fs/reiserfs/xattr.c:973
reiserfs_fill_super+0x20e5/0x2e90 fs/reiserfs/super.c:2174
mount_bdev+0x34d/0x410 fs/super.c:1401
legacy_get_tree+0x105/0x220 fs/fs_context.c:610
vfs_get_tree+0x89/0x2f0 fs/super.c:1531
do_new_mount fs/namespace.c:3145 [inline]
path_mount+0x1326/0x1e20 fs/namespace.c:3475
do_mount fs/namespace.c:3488 [inline]
__do_sys_mount fs/namespace.c:3696 [inline]
__se_sys_mount fs/namespace.c:3673 [inline]
__x64_sys_mount+0x27f/0x300 fs/namespace.c:3673
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&type->i_mutex_dir_key#6){+.+.}-{3:3}:
down_write+0x90/0x220 kernel/locking/rwsem.c:1562
inode_lock include/linux/fs.h:756 [inline]
chmod_common+0x14b/0x410 fs/open.c:600
vfs_fchmod fs/open.c:622 [inline]
__do_sys_fchmod fs/open.c:631 [inline]
__se_sys_fchmod fs/open.c:625 [inline]
__x64_sys_fchmod+0x10e/0x190 fs/open.c:625
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (sb_writers#9){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1792 [inline]
sb_start_write include/linux/fs.h:1867 [inline]
mnt_want_write_file+0x8e/0x590 fs/namespace.c:552
reiserfs_ioctl+0x19e/0x320 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]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

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

Possible unsafe locking scenario:

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

*** DEADLOCK ***

1 lock held by syz-executor418/5242:
#0: ffff888016eec090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x75/0xf0 fs/reiserfs/lock.c:27

stack backtrace:
CPU: 1 PID: 5242 Comm: syz-executor418 Not tainted 6.1.0-rc3-next-20221104-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1792 [inline]
sb_start_write include/linux/fs.h:1867 [inline]
mnt_want_write_file+0x8e/0x590 fs/namespace.c:552
reiserfs_ioctl+0x19e/0x320 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]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f157998c889
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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:00007ffe2dd23488 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f157998c889
RDX: 0000000000000000 RSI: 0000000040087602 RDI: 0000000000000005
RBP: 0000000000000000 R08: 00007f15799faec0 R09: 00007f15799faec0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe2dd234b0
R13: 0000000000000000 R14: 431bde82d7b634db R15: 0000000000000000
</TASK>

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