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SMTP id 5614622812f47-4af5e2c596cmr15023358b6e.16.1785750099497; Mon, 03 Aug 2026 02:41:39 -0700 (PDT) Date: Mon, 03 Aug 2026 02:41:39 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a706253.6ce73036.24301b.0026.GAE@google.com> Subject: [syzbot] [usb?] possible deadlock in uvcg_extension_allow_link From: syzbot To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 365f9c7a6b81 Merge branches 'for-next/core' and 'for-next/.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci console output: https://syzkaller.appspot.com/x/log.txt?x=14f3649e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=72c97575381cec47 dashboard link: https://syzkaller.appspot.com/bug?extid=b3410eb576b568216ae5 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 userspace arch: arm64 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10b83632580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15874aea580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/eafe0adb7386/disk-365f9c7a.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/29422d607579/vmlinux-365f9c7a.xz kernel image: https://storage.googleapis.com/syzbot-assets/98ca955a8b54/Image-365f9c7a.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b3410eb576b568216ae5@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.18/4919 is trying to acquire lock: ffff80008970de48 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_extension_allow_link+0x70/0x1f8 drivers/usb/gadget/function/uvc_configfs.c:1195 but task is already holding lock: ffff0000f06efa40 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff0000f06efa40 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: configfs_symlink+0x394/0xde0 fs/configfs/symlink.c:186 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] configfs_depend_item_unlocked+0x154/0x344 fs/configfs/dir.c:1259 usbg_make_tpg+0x230/0x4b4 drivers/usb/gadget/function/f_tcm.c:1686 target_fabric_make_tpg+0x98/0x518 drivers/target/target_core_fabric_configfs.c:939 configfs_mkdir+0x374/0x7d4 fs/configfs/dir.c:1360 vfs_mkdir+0x2dc/0x464 fs/namei.c:5276 filename_mkdirat+0x228/0x3f4 fs/namei.c:5309 __do_sys_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat fs/namei.c:5327 [inline] __arm64_sys_mkdirat+0x94/0xb8 fs/namei.c:5327 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #1 (&opts->dep_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x164/0xf14 kernel/locking/mutex.c:821 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874 tcm_set_name+0x34/0xd0 drivers/usb/gadget/function/f_tcm.c:2540 function_make+0x18c/0x300 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x374/0x7d4 fs/configfs/dir.c:1360 vfs_mkdir+0x2dc/0x464 fs/namei.c:5276 filename_mkdirat+0x228/0x3f4 fs/namei.c:5309 __do_sys_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat fs/namei.c:5327 [inline] __arm64_sys_mkdirat+0x94/0xb8 fs/namei.c:5327 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #0 (gadget_subsys.su_mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x17c0/0x2ebc kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x164/0xf14 kernel/locking/mutex.c:821 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874 uvcg_extension_allow_link+0x70/0x1f8 drivers/usb/gadget/function/uvc_configfs.c:1195 configfs_symlink+0x478/0xde0 fs/configfs/symlink.c:196 vfs_symlink+0x16c/0x290 fs/namei.c:5660 filename_symlinkat+0x18c/0x328 fs/namei.c:5685 __do_sys_symlinkat fs/namei.c:5705 [inline] __se_sys_symlinkat fs/namei.c:5700 [inline] __arm64_sys_symlinkat+0xa8/0xd4 fs/namei.c:5700 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 other info that might help us debug this: Chain exists of: gadget_subsys.su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#23 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#23); lock(&opts->dep_lock); lock(&sb->s_type->i_mutex_key#23); lock(gadget_subsys.su_mutex); *** DEADLOCK *** 2 locks held by syz.0.18/4919: #0: ffff0000c38e0450 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:494 #1: ffff0000f06efa40 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #1: ffff0000f06efa40 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: configfs_symlink+0x394/0xde0 fs/configfs/symlink.c:186 stack backtrace: CPU: 0 UID: 0 PID: 4919 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x328/0x330 kernel/locking/lockdep.c:2043 check_noncircular+0x158/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x17c0/0x2ebc kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x164/0xf14 kernel/locking/mutex.c:821 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:874 uvcg_extension_allow_link+0x70/0x1f8 drivers/usb/gadget/function/uvc_configfs.c:1195 configfs_symlink+0x478/0xde0 fs/configfs/symlink.c:196 vfs_symlink+0x16c/0x290 fs/namei.c:5660 filename_symlinkat+0x18c/0x328 fs/namei.c:5685 __do_sys_symlinkat fs/namei.c:5705 [inline] __se_sys_symlinkat fs/namei.c:5700 [inline] __arm64_sys_symlinkat+0xa8/0xd4 fs/namei.c:5700 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup