[syzbot] [lsm?] [integrity?] possible deadlock in ima_file_truncate

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c21bb4193868 Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113c53b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=448c2e24b1ceff13ed2a
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/dde4460fa7fd/disk-c21bb419.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e1fe13568a84/vmlinux-c21bb419.xz
kernel image: https://storage.googleapis.com/syzbot-assets/283184100427/bzImage-c21bb419.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+448c2e...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.857/8643 is trying to acquire lock:
ffff888037be2480 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: ima_reset_action_flags security/integrity/ima/ima_main.c:708 [inline]
ffff888037be2480 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: ima_reset_action_flags security/integrity/ima/ima_main.c:697 [inline]
ffff888037be2480 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: ima_file_truncate+0xe6/0x190 security/integrity/ima/ima_main.c:723

but task is already holding lock:
ffff888035fc0450 (sb_writers#6){.+.+}-{0:0}, at: do_open fs/namei.c:4693 [inline]
ffff888035fc0450 (sb_writers#6){.+.+}-{0:0}, at: path_openat+0x2929/0x4280 fs/namei.c:4863

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (sb_writers#6){.+.+}-{0:0}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_write include/linux/fs/super.h:125 [inline]
mnt_want_write+0x6f/0x410 fs/namespace.c:494
open_last_lookups fs/namei.c:4597 [inline]
path_openat+0xad9/0x4280 fs/namei.c:4860
do_file_open+0x20e/0x430 fs/namei.c:4892
file_open_name+0x1c3/0x3e0 fs/open.c:1326
filp_open+0x2e/0x50 fs/open.c:1343
nvmet_file_ns_enable+0x95/0x420 drivers/nvme/target/io-cmd-file.c:41
nvmet_ns_enable+0x35f/0x5d0 drivers/nvme/target/core.c:596
nvmet_ns_enable_store+0x11e/0x160 drivers/nvme/target/configfs.c:735
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&subsys->lock){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
nvmet_ns_device_path_store+0x57/0x1c0 drivers/nvme/target/configfs.c:536
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&p->frag_sem){.+.+}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
down_read+0x99/0x4c0 kernel/locking/rwsem.c:1574
fill_read_buffer fs/configfs/file.c:66 [inline]
configfs_read_iter+0x346/0x6f0 fs/configfs/file.c:88
__kernel_read+0x397/0xad0 fs/read_write.c:532
integrity_kernel_read+0x7e/0xb0 security/integrity/iint.c:28
ima_calc_file_hash_tfm+0x25e/0x350 security/integrity/ima/ima_crypto.c:222
ima_calc_file_hash+0x1e3/0x380 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x94f/0xb30 security/integrity/ima/ima_api.c:300
process_measurement+0xdfe/0x2350 security/integrity/ima/ima_main.c:425
ima_file_check+0xc3/0x110 security/integrity/ima/ima_main.c:685
security_file_post_open+0xc4/0x210 security/security.c:2755
do_open fs/namei.c:4702 [inline]
path_openat+0x985/0x4280 fs/namei.c:4863
do_file_open+0x20e/0x430 fs/namei.c:4892
do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&buffer->mutex){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
configfs_read_iter+0x79/0x6f0 fs/configfs/file.c:86
__kernel_read+0x397/0xad0 fs/read_write.c:532
integrity_kernel_read+0x7e/0xb0 security/integrity/iint.c:28
ima_calc_file_hash_tfm+0x25e/0x350 security/integrity/ima/ima_crypto.c:222
ima_calc_file_hash+0x1e3/0x380 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x94f/0xb30 security/integrity/ima/ima_api.c:300
process_measurement+0xdfe/0x2350 security/integrity/ima/ima_main.c:425
ima_file_check+0xc3/0x110 security/integrity/ima/ima_main.c:685
security_file_post_open+0xc4/0x210 security/security.c:2755
do_open fs/namei.c:4702 [inline]
path_openat+0x985/0x4280 fs/namei.c:4863
do_file_open+0x20e/0x430 fs/namei.c:4892
do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}:
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
ima_reset_action_flags security/integrity/ima/ima_main.c:708 [inline]
ima_reset_action_flags security/integrity/ima/ima_main.c:697 [inline]
ima_file_truncate+0xe6/0x190 security/integrity/ima/ima_main.c:723
security_file_truncate+0xf9/0x1e0 security/security.c:2771
handle_truncate fs/namei.c:4303 [inline]
do_open fs/namei.c:4704 [inline]
path_openat+0x3584/0x4280 fs/namei.c:4863
do_file_open+0x20e/0x430 fs/namei.c:4892
do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 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:
&ima_iint_mutex_key[depth] --> &subsys->lock --> sb_writers#6

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
rlock(sb_writers#6);
lock(&subsys->lock);
lock(sb_writers#6);
lock(&ima_iint_mutex_key[depth]);

*** DEADLOCK ***

1 lock held by syz.3.857/8643:
#0: ffff888035fc0450 (sb_writers#6){.+.+}-{0:0}, at: do_open fs/namei.c:4693 [inline]
#0: ffff888035fc0450 (sb_writers#6){.+.+}-{0:0}, at: path_openat+0x2929/0x4280 fs/namei.c:4863

stack backtrace:
CPU: 1 UID: 0 PID: 8643 Comm: syz.3.857 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
ima_reset_action_flags security/integrity/ima/ima_main.c:708 [inline]
ima_reset_action_flags security/integrity/ima/ima_main.c:697 [inline]
ima_file_truncate+0xe6/0x190 security/integrity/ima/ima_main.c:723
security_file_truncate+0xf9/0x1e0 security/security.c:2771
handle_truncate fs/namei.c:4303 [inline]
do_open fs/namei.c:4704 [inline]
path_openat+0x3584/0x4280 fs/namei.c:4863
do_file_open+0x20e/0x430 fs/namei.c:4892
do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3e7519e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3e7611c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f3e75426090 RCX: 00007f3e7519e0d9
RDX: 0000000000162e02 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f3e75235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3e75426128 R14: 00007f3e75426090 R15: 00007ffc1113bee8
</TASK>


---
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