Re: [syzbot] [ext4?] possible deadlock in process_measurement (6)
From: syzbot
Date: Sat Sep 05 2026 - 06:31:22 EST
syzbot has found a reproducer for the following issue on:
HEAD commit: 654ae5d73c05 Merge tag 'drm-fixes-2026-09-05' of https://g..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14c568f9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b454dc6b1b7acd30
dashboard link: https://syzkaller.appspot.com/bug?extid=c0bfa7a9a227036e8454
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12c568f9580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17cc6b49580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/49c1a99f815b/disk-654ae5d7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6fcecf1b8c8d/vmlinux-654ae5d7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fa54b23691ca/bzImage-654ae5d7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/7be96c47c44b/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=12041125580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c0bfa7a9a227036e8454@xxxxxxxxxxxxxxxxxxxxxxxxx
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor428/5602 is trying to acquire lock:
ffff88803f38b458 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: process_measurement+0x7e0/0x1c20 security/integrity/ima/ima_main.c:319
but task is already holding lock:
ffff888038eee198 (&common->filesem){++++}-{4:4}, at: fsg_store_file+0x163/0x400 drivers/usb/gadget/function/storage_common.c:452
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&common->filesem){++++}-{4:4}:
down_read+0x97/0x200 kernel/locking/rwsem.c:1574
fsg_show_file+0x2d/0x140 drivers/usb/gadget/function/storage_common.c:339
fill_read_buffer fs/configfs/file.c:68 [inline]
configfs_read_iter+0x2ba/0x620 fs/configfs/file.c:88
__kernel_read+0x4d3/0x970 fs/read_write.c:532
integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
ima_calc_file_hash+0x45d/0x8a0 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x521/0xa10 security/integrity/ima/ima_api.c:300
process_measurement+0x1282/0x1c20 security/integrity/ima/ima_main.c:425
ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
security_file_post_open+0xb3/0x260 security/security.c:2755
do_open fs/namei.c:4839 [inline]
path_openat+0x148a/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
do_sys_openat2+0x115/0x200 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&p->frag_sem){.+.+}-{4:4}:
down_read+0x97/0x200 kernel/locking/rwsem.c:1574
fill_read_buffer fs/configfs/file.c:66 [inline]
configfs_read_iter+0x1cf/0x620 fs/configfs/file.c:88
__kernel_read+0x4d3/0x970 fs/read_write.c:532
integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
ima_calc_file_hash+0x45d/0x8a0 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x521/0xa10 security/integrity/ima/ima_api.c:300
process_measurement+0x1282/0x1c20 security/integrity/ima/ima_main.c:425
ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
security_file_post_open+0xb3/0x260 security/security.c:2755
do_open fs/namei.c:4839 [inline]
path_openat+0x148a/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
do_sys_openat2+0x115/0x200 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&buffer->mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
configfs_read_iter+0x73/0x620 fs/configfs/file.c:86
__kernel_read+0x4d3/0x970 fs/read_write.c:532
integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
ima_calc_file_hash+0x45d/0x8a0 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x521/0xa10 security/integrity/ima/ima_api.c:300
process_measurement+0x1282/0x1c20 security/integrity/ima/ima_main.c:425
ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
security_file_post_open+0xb3/0x260 security/security.c:2755
do_open fs/namei.c:4839 [inline]
path_openat+0x148a/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
do_sys_openat2+0x115/0x200 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3181 [inline]
check_prevs_add kernel/locking/lockdep.c:3300 [inline]
validate_chain kernel/locking/lockdep.c:3924 [inline]
__lock_acquire+0x15ff/0x2e40 kernel/locking/lockdep.c:5254
lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
process_measurement+0x7e0/0x1c20 security/integrity/ima/ima_main.c:319
ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
security_file_post_open+0xb3/0x260 security/security.c:2755
do_open fs/namei.c:4839 [inline]
path_openat+0x148a/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
file_open_name fs/open.c:1375 [inline]
filp_open+0x16d/0x1d0 fs/open.c:1392
fsg_lun_open+0x6c/0xe00 drivers/usb/gadget/function/storage_common.c:194
fsg_store_file+0x19e/0x400 drivers/usb/gadget/function/storage_common.c:455
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
&ima_iint_mutex_key[depth] --> &p->frag_sem --> &common->filesem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&common->filesem);
lock(&p->frag_sem);
lock(&common->filesem);
lock(&ima_iint_mutex_key[depth]);
*** DEADLOCK ***
locks held by syz-executor428/5602: 4, last CPU#0:
#0: ffff88801d734510 (sb_writers#8){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#0: ffff88801d734510 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#1: ffff888028b16678 (&buffer->mutex){+.+.}-{4:4}, at: configfs_write_iter+0x81/0x430 fs/configfs/file.c:226
#2: ffff888025f30b68 (&p->frag_sem){.+.+}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
#2: ffff888025f30b68 (&p->frag_sem){.+.+}-{4:4}, at: configfs_write_iter+0x23b/0x430 fs/configfs/file.c:229
#3: ffff888038eee198 (&common->filesem){++++}-{4:4}, at: fsg_store_file+0x163/0x400 drivers/usb/gadget/function/storage_common.c:452
stack backtrace:
CPU: 0 UID: 0 PID: 5602 Comm: syz-executor428 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059
check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191
check_prev_add kernel/locking/lockdep.c:3181 [inline]
check_prevs_add kernel/locking/lockdep.c:3300 [inline]
validate_chain kernel/locking/lockdep.c:3924 [inline]
__lock_acquire+0x15ff/0x2e40 kernel/locking/lockdep.c:5254
lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
process_measurement+0x7e0/0x1c20 security/integrity/ima/ima_main.c:319
ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
security_file_post_open+0xb3/0x260 security/security.c:2755
do_open fs/namei.c:4839 [inline]
path_openat+0x148a/0x1d60 fs/namei.c:5000
do_file_open+0x23e/0x4a0 fs/namei.c:5029
file_open_name fs/open.c:1375 [inline]
filp_open+0x16d/0x1d0 fs/open.c:1392
fsg_lun_open+0x6c/0xe00 drivers/usb/gadget/function/storage_common.c:194
fsg_store_file+0x19e/0x400 drivers/usb/gadget/function/storage_common.c:455
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f29897e19a9
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe566936c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00002000000002c0 RCX: 00007f29897e19a9
RDX: 0000000000000005 RSI: 00002000000003c0 RDI: 0000000000000005
RBP: 0000200000000200 R08: 00005555573c7560 R09: 00005555573c7560
R10: 00005555573c7560 R11: 0000000000000246 R12: 6769666e6f632f2e
R13: 0000000000000002 R14: 431bde82d7b634db R15: 00007f298984104b
</TASK>
mass_storage.0/lun.0: file too small: file0
---
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#syz test: git://repo/address.git branch-or-commit-hash
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