[v6.6] possible deadlock in attr_data_get_block

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f5b4c104b7d Linux 6.6.95
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14a9708c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b80883c3ded77c16
dashboard link: https://syzkaller.appspot.com/bug?extid=08019e91be38802a5b96
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0efd4e01816e/disk-3f5b4c10.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7c9d20858cc/vmlinux-3f5b4c10.xz
kernel image: https://storage.googleapis.com/syzbot-assets/18f8dc74ef68/bzImage-3f5b4c10.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08019e...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 4096
======================================================
WARNING: possible circular locking dependency detected
6.6.95-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1429/11465 is trying to acquire lock:
ffff88823bd5c100 (&ni->ni_lock#2/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1120 [inline]
ffff88823bd5c100 (&ni->ni_lock#2/5){+.+.}-{3:3}, at: attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918

but task is already holding lock:
ffff8880782ff3a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
ffff8880782ff3a0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
__might_fault+0xc6/0x120 mm/memory.c:5946
_copy_to_user+0x2a/0xa0 lib/usercopy.c:36
copy_to_user include/linux/uaccess.h:191 [inline]
fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
ni_fiemap+0x7e6/0xbe0 fs/ntfs3/frecord.c:2038
ntfs_fiemap+0xdb/0x130 fs/ntfs3/file.c:1213
ioctl_fiemap fs/ioctl.c:220 [inline]
do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
__do_sys_ioctl fs/ioctl.c:869 [inline]
__se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ni->ni_lock#2/5){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
ni_lock fs/ntfs3/ntfs_fs.h:1120 [inline]
attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918
ntfs_file_mmap+0x4b8/0x730 fs/ntfs3/file.c:294
call_mmap include/linux/fs.h:2023 [inline]
mmap_file mm/internal.h:98 [inline]
__mmap_region mm/mmap.c:2786 [inline]
mmap_region+0xe57/0x1f80 mm/mmap.c:2937
do_mmap+0x8d1/0xfd0 mm/mmap.c:1381
vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1427
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&mm->mmap_lock);
lock(&ni->ni_lock#2/5);
lock(&mm->mmap_lock);
lock(&ni->ni_lock#2/5);

*** DEADLOCK ***

1 lock held by syz.2.1429/11465:
#0: ffff8880782ff3a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
#0: ffff8880782ff3a0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554

stack backtrace:
CPU: 1 PID: 11465 Comm: syz.2.1429 Not tainted 6.6.95-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
ni_lock fs/ntfs3/ntfs_fs.h:1120 [inline]
attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918
ntfs_file_mmap+0x4b8/0x730 fs/ntfs3/file.c:294
call_mmap include/linux/fs.h:2023 [inline]
mmap_file mm/internal.h:98 [inline]
__mmap_region mm/mmap.c:2786 [inline]
mmap_region+0xe57/0x1f80 mm/mmap.c:2937
do_mmap+0x8d1/0xfd0 mm/mmap.c:1381
vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1427
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f480b78e929
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f480c64d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f480b9b5fa0 RCX: 00007f480b78e929
RDX: 0000000000000002 RSI: 0000000000001000 RDI: 0000200000001000
RBP: 00007f480b810b39 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f480b9b5fa0 R15: 00007ffc53178c98
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: e5bbb12db2c7 Linux 6.6.115
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1540cbcd980000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=08019e91be38802a5b96
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12059258580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=112a5932580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e6860876f0ec/disk-e5bbb12d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d6c28d7cc7f3/vmlinux-e5bbb12d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f52ba3964b2/bzImage-e5bbb12d.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/e38ea0e1765e/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/c287044aec71/mount_4.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08019e...@syzkaller.appspotmail.com

ntfs3: loop2: ino=b, Correct links count -> 1.
ntfs3: loop2: Mark volume as dirty due to NTFS errors

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

syzkaller #0 Not tainted
------------------------------------------------------
syz.2.36/6043 is trying to acquire lock:
ffff888073ec9720 (&ni->ni_lock/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1119 [inline]
ffff888073ec9720 (&ni->ni_lock/5){+.+.}-{3:3}, at: attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918

but task is already holding lock:

ffff88807a1594a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
ffff88807a1594a0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
__might_fault+0xc6/0x120 mm/memory.c:5946
_copy_to_user+0x2a/0xa0 lib/usercopy.c:36
copy_to_user include/linux/uaccess.h:191 [inline]
fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
ni_fiemap+0x7e6/0xbe0 fs/ntfs3/frecord.c:2038

ntfs_fiemap+0xdb/0x130 fs/ntfs3/file.c:1216

ioctl_fiemap fs/ioctl.c:220 [inline]
do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
__do_sys_ioctl fs/ioctl.c:869 [inline]
__se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ni->ni_lock/5){+.+.}-{3:3}:

check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747

ni_lock fs/ntfs3/ntfs_fs.h:1119 [inline]
attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918
ntfs_file_mmap+0x4c0/0x760 fs/ntfs3/file.c:294

call_mmap include/linux/fs.h:2023 [inline]
mmap_file mm/internal.h:98 [inline]

__mmap_region mm/mmap.c:2790 [inline]
mmap_region+0xfa5/0x2020 mm/mmap.c:2941
do_mmap+0x92f/0x10a0 mm/mmap.c:1385
vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431

do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&mm->mmap_lock);

lock(&ni->ni_lock/5);
lock(&mm->mmap_lock);
lock(&ni->ni_lock/5);

*** DEADLOCK ***

1 lock held by syz.2.36/6043:
#0: ffff88807a1594a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:124 [inline]
#0: ffff88807a1594a0 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x168/0x400 mm/util.c:554

stack backtrace:
CPU: 0 PID: 6043 Comm: syz.2.36 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025

Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747

ni_lock fs/ntfs3/ntfs_fs.h:1119 [inline]
attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918
ntfs_file_mmap+0x4c0/0x760 fs/ntfs3/file.c:294

call_mmap include/linux/fs.h:2023 [inline]
mmap_file mm/internal.h:98 [inline]

__mmap_region mm/mmap.c:2790 [inline]
mmap_region+0xfa5/0x2020 mm/mmap.c:2941
do_mmap+0x92f/0x10a0 mm/mmap.c:1385
vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431

do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7f8be538efc9

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 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007ffca87a33b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f8be55e5fa0 RCX: 00007f8be538efc9
RDX: 00000000027ffff7 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007f8be5411f91 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000004012011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8be55e5fa0 R14: 00007f8be55e5fa0 R15: 0000000000000006
</TASK>


---
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