possible deadlock in uvcg_streaming_header_allow_link

Status: upstream: reported on 2026/07/25 09:58
Reported-by: syzbot+bc03bb5f2dbff6d1ecb9@syzkaller.appspotmail.com
First crash: 12d, last: 10h41m
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in uvcg_streaming_header_allow_link 4 24 7h50m 8d22h 0/3 upstream: reported on 2026/07/29 09:31
upstream possible deadlock in uvcg_streaming_header_allow_link usb prio:low 4 syz, C error 269 26m 9d18h 0/29 upstream: reported C repro on 2026/07/28 13:41
linux-6.6 possible deadlock in uvcg_streaming_header_allow_link 4 12 2d08h 12d 0/2 upstream: reported on 2026/07/25 16:46

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.718/7527 is trying to acquire lock:
ffffffff8ceceff0 (gadget_subsys.su_mutex){+.+.}-{3:3}, at: uvcg_streaming_header_allow_link+0x6d/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:942

but task is already holding lock:
ffff88804d890150 (&sb->s_type->i_mutex_key#24){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
ffff88804d890150 (&sb->s_type->i_mutex_key#24){++++}-{3:3}, at: configfs_symlink+0x47b/0x13b0 fs/configfs/symlink.c:192

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sb->s_type->i_mutex_key#24){++++}-{3:3}:
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       inode_lock include/linux/fs.h:787 [inline]
       configfs_depend_item_unlocked+0x14f/0x430 fs/configfs/dir.c:1255
       usbg_make_tpg+0x1f3/0x580 drivers/usb/gadget/function/f_tcm.c:1351
       target_fabric_make_tpg+0xa0/0x6d0 drivers/target/target_core_fabric_configfs.c:837
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4073
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&opts->dep_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       tcm_set_name+0x26/0x90 drivers/usb/gadget/function/f_tcm.c:2224
       function_make+0x195/0x350 drivers/usb/gadget/configfs.c:620
       configfs_mkdir+0x511/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x386/0x570 fs/namei.c:4073
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (gadget_subsys.su_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       uvcg_streaming_header_allow_link+0x6d/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:942
       configfs_symlink+0x5a4/0x13b0 fs/configfs/symlink.c:202
       vfs_symlink+0x245/0x3d0 fs/namei.c:4437
       do_symlinkat+0x1ab/0x6b0 fs/namei.c:4466
       __do_sys_symlinkat fs/namei.c:4483 [inline]
       __se_sys_symlinkat fs/namei.c:4480 [inline]
       __x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4480
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  gadget_subsys.su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#24

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sb->s_type->i_mutex_key#24);
                               lock(&opts->dep_lock);
                               lock(&sb->s_type->i_mutex_key#24);
  lock(gadget_subsys.su_mutex);

 *** DEADLOCK ***

2 locks held by syz.3.718/7527:
 #0: ffff88814664a460 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
 #1: ffff88804d890150 (&sb->s_type->i_mutex_key#24){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff88804d890150 (&sb->s_type->i_mutex_key#24){++++}-{3:3}, at: configfs_symlink+0x47b/0x13b0 fs/configfs/symlink.c:192

stack backtrace:
CPU: 1 PID: 7527 Comm: syz.3.718 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 uvcg_streaming_header_allow_link+0x6d/0x4a0 drivers/usb/gadget/function/uvc_configfs.c:942
 configfs_symlink+0x5a4/0x13b0 fs/configfs/symlink.c:202
 vfs_symlink+0x245/0x3d0 fs/namei.c:4437
 do_symlinkat+0x1ab/0x6b0 fs/namei.c:4466
 __do_sys_symlinkat fs/namei.c:4483 [inline]
 __se_sys_symlinkat fs/namei.c:4480 [inline]
 __x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4480
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f916358c0d9
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:00007f91617e4028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007f9163813fa0 RCX: 00007f916358c0d9
RDX: 00002000000003c0 RSI: ffffffffffffff9c RDI: 0000200000000380
RBP: 00007f9163623024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9163814038 R14: 00007f9163813fa0 R15: 00007ffc5b2a04d8
 </TASK>

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/06 21:47 linux-5.15.y 9c7634c60784 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/06 21:46 linux-5.15.y 9c7634c60784 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/04 02:48 linux-5.15.y 6e2fd6534337 9451e17e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/03 15:47 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/03 15:35 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/03 14:51 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/01 07:06 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/01 06:54 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/01 06:54 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/01 06:28 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/08/01 06:27 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/31 16:30 linux-5.15.y 6e2fd6534337 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/31 16:29 linux-5.15.y 6e2fd6534337 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/31 16:28 linux-5.15.y 6e2fd6534337 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/30 11:34 linux-5.15.y 674f684f7c61 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/28 06:33 linux-5.15.y 674f684f7c61 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/25 09:57 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
2026/07/25 09:57 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in uvcg_streaming_header_allow_link
* Struck through repros no longer work on HEAD.