[syzbot] [ntfs3?] possible deadlock in ntfs_unlink_inode (2)

syzbot
2025-05-08T08:52:40Z

Hello,

syzbot found the following issue on:

HEAD commit: 2a239ffbebb5 Merge tag 'sound-6.15-rc5' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157fe0f4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a42a9d552788177b
dashboard link: https://syzkaller.appspot.com/bug?extid=dab475abf94f7513eb9f
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/39057b073d40/disk-2a239ffb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c82b778f8922/vmlinux-2a239ffb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/000bd0cd2b5e/bzImage-2a239ffb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dab475abf94f7513eb9f@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc4-syzkaller-00291-g2a239ffbebb5 #0 Not tainted
------------------------------------------------------
syz-executor/11002 is trying to acquire lock:
ffff88805a314318 (&ni->ni_lock#3/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1105 [inline]
ffff88805a314318 (&ni->ni_lock#3/5){+.+.}-{4:4}, at: ntfs_unlink_inode+0x273/0x6a0 fs/ntfs3/inode.c:1728

but task is already holding lock:
ffff88805a3125b8 (&ni->ni_lock/6){+.+.}-{4:4}, at: ni_lock_dir fs/ntfs3/ntfs_fs.h:1110 [inline]
ffff88805a3125b8 (&ni->ni_lock/6){+.+.}-{4:4}, at: ntfs_rmdir+0xb6/0xf0 fs/ntfs3/namei.c:222

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&ni->ni_lock/6){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
__mutex_lock_common kernel/locking/mutex.c:601 [inline]
__mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
ni_lock_dir fs/ntfs3/ntfs_fs.h:1110 [inline]
ntfs_unlink+0xb6/0xf0 fs/ntfs3/namei.c:177
vfs_unlink+0x391/0x650 fs/namei.c:4579
do_unlinkat+0x350/0x560 fs/namei.c:4643
__do_sys_unlinkat fs/namei.c:4684 [inline]
__se_sys_unlinkat fs/namei.c:4677 [inline]
__x64_sys_unlinkat+0xd3/0xf0 fs/namei.c:4677
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&sb->s_type->i_mutex_key#26){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
inode_lock include/linux/fs.h:867 [inline]
ntfs_file_mmap+0x525/0x730 fs/ntfs3/file.c:397
call_mmap include/linux/fs.h:2243 [inline]
mmap_file mm/internal.h:167 [inline]
__mmap_new_file_vma mm/vma.c:2353 [inline]
__mmap_new_vma mm/vma.c:2417 [inline]
__mmap_region mm/vma.c:2519 [inline]
mmap_region+0x103b/0x1e50 mm/vma.c:2597
do_mmap+0xc68/0x1100 mm/mmap.c:561
vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579
ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:607
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&mm->mmap_lock){++++}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
__might_fault+0xcc/0x130 mm/memory.c:7151
_inline_copy_to_user include/linux/uaccess.h:192 [inline]
_copy_to_user+0x2c/0xb0 lib/usercopy.c:26
copy_to_user include/linux/uaccess.h:225 [inline]
fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145
ni_fiemap+0x89c/0xbf0 fs/ntfs3/frecord.c:2007
ntfs_fiemap+0xda/0x130 fs/ntfs3/file.c:1380
ioctl_fiemap fs/ioctl.c:220 [inline]
do_vfs_ioctl+0x1638/0x1eb0 fs/ioctl.c:840
__do_sys_ioctl fs/ioctl.c:904 [inline]
__se_sys_ioctl+0x82/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ni->ni_lock#3/5){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3166 [inline]
check_prevs_add kernel/locking/lockdep.c:3285 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
__lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
__mutex_lock_common kernel/locking/mutex.c:601 [inline]
__mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
ni_lock fs/ntfs3/ntfs_fs.h:1105 [inline]
ntfs_unlink_inode+0x273/0x6a0 fs/ntfs3/inode.c:1728
ntfs_rmdir+0xc1/0xf0 fs/ntfs3/namei.c:224
vfs_rmdir+0x3b7/0x520 fs/namei.c:4454
do_rmdir+0x2ac/0x630 fs/namei.c:4509
__do_sys_unlinkat fs/namei.c:4683 [inline]
__se_sys_unlinkat fs/namei.c:4677 [inline]
__x64_sys_unlinkat+0xc2/0xf0 fs/namei.c:4677
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
&ni->ni_lock#3/5 --> &sb->s_type->i_mutex_key#26 --> &ni->ni_lock/6

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&ni->ni_lock/6);
lock(&sb->s_type->i_mutex_key#26);
lock(&ni->ni_lock/6);
lock(&ni->ni_lock#3/5);

*** DEADLOCK ***

4 locks held by syz-executor/11002:
#0: ffff88803057a420 (sb_writers#18){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:556
#1: ffff88805a312850 (&type->i_mutex_dir_key#10/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:902 [inline]
#1: ffff88805a312850 (&type->i_mutex_dir_key#10/1){+.+.}-{4:4}, at: do_rmdir+0x1b2/0x630 fs/namei.c:4501
#2: ffff88805a3145b0 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
#2: ffff88805a3145b0 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: vfs_rmdir+0xf7/0x520 fs/namei.c:4443
#3: ffff88805a3125b8 (&ni->ni_lock/6){+.+.}-{4:4}, at: ni_lock_dir fs/ntfs3/ntfs_fs.h:1110 [inline]
#3: ffff88805a3125b8 (&ni->ni_lock/6){+.+.}-{4:4}, at: ntfs_rmdir+0xb6/0xf0 fs/ntfs3/namei.c:222

stack backtrace:
CPU: 1 UID: 0 PID: 11002 Comm: syz-executor Not tainted 6.15.0-rc4-syzkaller-00291-g2a239ffbebb5 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2079
check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211
check_prev_add kernel/locking/lockdep.c:3166 [inline]
check_prevs_add kernel/locking/lockdep.c:3285 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
__lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
__mutex_lock_common kernel/locking/mutex.c:601 [inline]
__mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
ni_lock fs/ntfs3/ntfs_fs.h:1105 [inline]
ntfs_unlink_inode+0x273/0x6a0 fs/ntfs3/inode.c:1728
ntfs_rmdir+0xc1/0xf0 fs/ntfs3/namei.c:224
vfs_rmdir+0x3b7/0x520 fs/namei.c:4454
do_rmdir+0x2ac/0x630 fs/namei.c:4509
__do_sys_unlinkat fs/namei.c:4683 [inline]
__se_sys_unlinkat fs/namei.c:4677 [inline]
__x64_sys_unlinkat+0xc2/0xf0 fs/namei.c:4677
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f21ac98df47
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 07 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffff76a6458 EFLAGS: 00000207 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007f21ac98df47
RDX: 0000000000000200 RSI: 00007ffff76a7600 RDI: 00000000ffffff9c
RBP: 00007f21aca1089d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000207 R12: 00007ffff76a7600
R13: 00007f21aca1089d R14: 000000000006bff7 R15: 00007ffff76a97c0
</TASK>

---
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 syzkaller@googlegroups.com.

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

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup