From: syzbot <syzbot+c39ae720fb00e7e6f14b@syzkaller.appspotmail.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [syzbot] [usb?] possible deadlock in lookup_open
Date: Sat, 22 Aug 2026 00:43:32 -0700 [thread overview]
Message-ID: <6a895324.ae6ddae5.3da009.0053.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 531ed942bb0d Merge tag 'fbdev-for-7.3-rc1' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14d98179580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac80ca7ed8b5e2fa
dashboard link: https://syzkaller.appspot.com/bug?extid=c39ae720fb00e7e6f14b
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/6416befe19e7/disk-531ed942.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1c4b8543f98e/vmlinux-531ed942.xz
kernel image: https://storage.googleapis.com/syzbot-assets/db9600966ac4/bzImage-531ed942.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c39ae720fb00e7e6f14b@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
syz.1.6874/28240 is trying to acquire lock:
ffff8880493ca460 (sb_writers#6){.+.+}-{0:0}, at: lookup_open+0x150/0x1990 fs/namei.c:4451
but task is already holding lock:
ffff88802b876920 (&common->filesem){++++}-{4:4}, at: fsg_store_file+0x193/0x450 drivers/usb/gadget/function/storage_common.c:452
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (&common->filesem){++++}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5886 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5843
down_read+0x99/0x4c0 kernel/locking/rwsem.c:1574
fsg_show_file+0x20/0x180 drivers/usb/gadget/function/storage_common.c:339
fill_read_buffer fs/configfs/file.c:68 [inline]
configfs_read_iter+0x426/0x6f0 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:4839 [inline]
path_openat+0x5cd/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 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+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (&p->frag_sem){++++}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5886 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5843
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:4839 [inline]
path_openat+0x5cd/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 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+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&buffer->mutex){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5886 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5843
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bc0 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:4839 [inline]
path_openat+0x5cd/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 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+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5886 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5843
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bc0 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:4298 [inline]
do_open fs/namei.c:4841 [inline]
path_openat+0x1d7e/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 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+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (sb_writers#6){.+.+}-{0:0}:
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
check_prevs_add kernel/locking/lockdep.c:3300 [inline]
validate_chain kernel/locking/lockdep.c:3924 [inline]
__lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5253
lock_acquire kernel/locking/lockdep.c:5886 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5843
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/0x420 fs/namespace.c:494
lookup_open+0x150/0x1990 fs/namei.c:4451
open_last_lookups fs/namei.c:4767 [inline]
path_openat+0xa2c/0x2440 fs/namei.c:4997
do_file_open+0x20e/0x430 fs/namei.c:5029
file_open_name+0x1c3/0x3e0 fs/open.c:1375
filp_open+0x2e/0x50 fs/open.c:1392
fsg_lun_open+0x6b/0x7b0 drivers/usb/gadget/function/storage_common.c:194
fsg_store_file+0x1e7/0x450 drivers/usb/gadget/function/storage_common.c:455
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 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:
sb_writers#6 --> &p->frag_sem --> &common->filesem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&common->filesem);
lock(&p->frag_sem);
lock(&common->filesem);
rlock(sb_writers#6);
*** DEADLOCK ***
locks held by syz.1.6874/28240: 5, last CPU#1:
#0: ffff88807b5895f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
#1: ffff88801e7c6460 (sb_writers#15){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
#2: ffff888057321a80 (&buffer->mutex){+.+.}-{4:4}, at: configfs_write_iter+0x76/0x4e0 fs/configfs/file.c:226
#3: ffff888027e93070 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
#3: ffff888027e93070 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x218/0x4e0 fs/configfs/file.c:229
#4: ffff88802b876920 (&common->filesem){++++}-{4:4}, at: fsg_store_file+0x193/0x450 drivers/usb/gadget/function/storage_common.c:452
stack backtrace:
CPU: 1 UID: 0 PID: 28240 Comm: syz.1.6874 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
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+0x178/0x1be kernel/locking/lockdep.c:2059
check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2191
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
check_prevs_add kernel/locking/lockdep.c:3300 [inline]
validate_chain kernel/locking/lockdep.c:3924 [inline]
__lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5253
lock_acquire kernel/locking/lockdep.c:5886 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5843
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/0x420 fs/namespace.c:494
lookup_open+0x150/0x1990 fs/namei.c:4451
open_last_lookups fs/namei.c:4767 [inline]
path_openat+0xa2c/0x2440 fs/namei.c:4997
do_file_open+0x20e/0x430 fs/namei.c:5029
file_open_name+0x1c3/0x3e0 fs/open.c:1375
filp_open+0x2e/0x50 fs/open.c:1392
fsg_lun_open+0x6b/0x7b0 drivers/usb/gadget/function/storage_common.c:194
fsg_store_file+0x1e7/0x450 drivers/usb/gadget/function/storage_common.c:455
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd1a199e0d9
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:00007fd1a28c8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd1a1c25fa0 RCX: 00007fd1a199e0d9
RDX: 0000000000000005 RSI: 00002000000003c0 RDI: 0000000000000004
RBP: 00007fd1a1a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd1a1c26038 R14: 00007fd1a1c25fa0 R15: 00007ffc4e5fb158
</TASK>
mass_storage.0/lun.0: unable to open backing file: file0
---
This report is generated by a bot. It may contain errors.
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next reply other threads:[~2026-08-22 7:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-22 7:43 syzbot [this message]
2026-09-25 8:02 ` [syzbot] [usb?] possible deadlock in lookup_open syzbot
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