* Re: [syzbot] [ext4?] possible deadlock in process_measurement (6)
2026-09-05 10:30 ` [syzbot] [ext4?] possible deadlock in process_measurement (6) syzbot
@ 2026-09-08 1:15 ` Mimi Zohar
0 siblings, 0 replies; 2+ messages in thread
From: Mimi Zohar @ 2026-09-08 1:15 UTC (permalink / raw)
To: syzbot, dmitry.kasatkin, eric.snowberg, gregkh, jmorris,
linux-ext4, linux-integrity, linux-kernel, linux-security-module,
linux-usb, paul, roberto.sassu, serge, syzkaller-bugs
On Sat, 2026-09-05 at 03:30 -0700, syzbot wrote:
> 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@syzkaller.appspotmail.com
The patches for excluding IMA measure and appraise rules for configfs were
upstreamed in 7.3-rc2:
8e22ce504f8a ("ima: don't measure/appraise files on configfs")
ab84c314417e ("configfs: move CONFIGFS_MAGIC definition to magic.h")
Mimi
>
> ======================================================
> 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
>
>
> ---
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
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