On Wed, Feb 7, 2024 at 5:44 PM syzbot <syzbot+3b1d4b3d5f7a358bf9a9@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: ed5551279c91 Merge 6.8-rc3 into usb-next > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing > console output: https://syzkaller.appspot.com/x/log.txt?x=16940d7be80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=28a3704ea90ef255 > dashboard link: https://syzkaller.appspot.com/bug?extid=3b1d4b3d5f7a358bf9a9 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14450a38180000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1603629fe80000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/10b543a7171a/disk-ed555127.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/dc10f27643e8/vmlinux-ed555127.xz > kernel image: https://storage.googleapis.com/syzbot-assets/bb6389e754b9/bzImage-ed555127.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+3b1d4b3d5f7a358bf9a9@xxxxxxxxxxxxxxxxxxxxxxxxx > > usb 1-1: SerialNumber: syz > usb 1-1: config 0 descriptor?? > usbtv 1-1:0.0: Fushicai USBTV007 Audio-Video Grabber > usb 1-1: USB disconnect, device number 2 > ============================================ > WARNING: possible recursive locking detected > 6.8.0-rc3-syzkaller-00047-ged5551279c91 #0 Not tainted > -------------------------------------------- > kworker/0:2/694 is trying to acquire lock: > ffff888109f20b70 (&usbtv->vb2q_lock){+.+.}-{3:3}, at: vb2_video_unregister_device drivers/media/common/videobuf2/videobuf2-v4l2.c:1269 [inline] > ffff888109f20b70 (&usbtv->vb2q_lock){+.+.}-{3:3}, at: vb2_video_unregister_device+0x12b/0x2d0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1245 > > but task is already holding lock: > ffff888109f20b70 (&usbtv->vb2q_lock){+.+.}-{3:3}, at: usbtv_video_free+0x28/0x70 drivers/media/usb/usbtv/usbtv-video.c:966 > Looking at usbtv_video_free [1], it calls vb2_video_unregister_device() with the queue mutex locked, which is just wrong. I wonder how (and if) it even worked before. Laurent, Hans, Mauro, any idea who is maintaining this driver? I don't see a matching entry in the MAINTAINERS file. [1] https://elixir.bootlin.com/linux/v6.8-rc4/source/drivers/media/usb/usbtv/usbtv-video.c#L964 Best regards, Tomasz > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&usbtv->vb2q_lock); > lock(&usbtv->vb2q_lock); > > *** DEADLOCK *** > > May be due to missing lock nesting notation > > 7 locks held by kworker/0:2/694: > #0: ffff888106ad2138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x789/0x15d0 kernel/workqueue.c:2608 > #1: ffffc90001c0fd80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7eb/0x15d0 kernel/workqueue.c:2609 > #2: ffff88810af2f190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:990 [inline] > #2: ffff88810af2f190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1be/0x4f40 drivers/usb/core/hub.c:5840 > #3: ffff888107799190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:990 [inline] > #3: ffff888107799190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x10a/0x910 drivers/usb/core/hub.c:2287 > #4: ffff88810779a160 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:990 [inline] > #4: ffff88810779a160 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1095 [inline] > #4: ffff88810779a160 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1292 > #5: ffff888109f20b70 (&usbtv->vb2q_lock){+.+.}-{3:3}, at: usbtv_video_free+0x28/0x70 drivers/media/usb/usbtv/usbtv-video.c:966 > #6: ffff888109f20ae0 (&usbtv->v4l2_lock){+.+.}-{3:3}, at: usbtv_video_free+0x32/0x70 drivers/media/usb/usbtv/usbtv-video.c:967 > > stack backtrace: > CPU: 0 PID: 694 Comm: kworker/0:2 Not tainted 6.8.0-rc3-syzkaller-00047-ged5551279c91 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 > Workqueue: usb_hub_wq hub_event > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 > check_deadlock kernel/locking/lockdep.c:3062 [inline] > validate_chain kernel/locking/lockdep.c:3856 [inline] > __lock_acquire+0x210a/0x3b30 kernel/locking/lockdep.c:5137 > lock_acquire kernel/locking/lockdep.c:5754 [inline] > lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719 > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:752 > vb2_video_unregister_device drivers/media/common/videobuf2/videobuf2-v4l2.c:1269 [inline] > vb2_video_unregister_device+0x12b/0x2d0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1245 > usbtv_video_free+0x4a/0x70 drivers/media/usb/usbtv/usbtv-video.c:970 > usbtv_disconnect+0x5c/0xd0 drivers/media/usb/usbtv/usbtv-core.c:138 > usb_unbind_interface+0x1e5/0x960 drivers/usb/core/driver.c:461 > device_remove drivers/base/dd.c:569 [inline] > device_remove+0x11f/0x170 drivers/base/dd.c:561 > __device_release_driver drivers/base/dd.c:1272 [inline] > device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1295 > bus_remove_device+0x22c/0x420 drivers/base/bus.c:574 > device_del+0x39a/0xa50 drivers/base/core.c:3814 > usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1416 > usb_disconnect+0x2e1/0x910 drivers/usb/core/hub.c:2296 > hub_port_connect drivers/usb/core/hub.c:5352 [inline] > hub_port_connect_change drivers/usb/core/hub.c:5652 [inline] > port_event drivers/usb/core/hub.c:5812 [inline] > hub_event+0x1be0/0x4f40 drivers/usb/core/hub.c:5894 > process_one_work+0x886/0x15d0 kernel/workqueue.c:2633 > process_scheduled_works kernel/workqueue.c:2706 [inline] > worker_thread+0x8b9/0x1290 kernel/workqueue.c:2787 > kthread+0x2c6/0x3a0 kernel/kthread.c:388 > ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 > </TASK> > > > --- > 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@xxxxxxxxxxxxxxxx. > > 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
