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Sun, 01 Nov 2026 08:37:31 -0800 (PST) Date: Sun, 01 Nov 2026 08:37:31 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ae76acb.7fe51036.1ecf7.002b.GAE@google.com> Subject: [moderation/CI] Re: media: em28xx: fix v4l2 use-after-free after failed init From: syzbot ci To: syzkaller-upstream-moderation@googlegroups.com Cc: syzbot@lists.linux.dev Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v1] media: em28xx: fix v4l2 use-after-free after failed init https://lore.kernel.org/all/20261031204723.1415-1-drifabdelmalekmohamedsaid@gmail.com * [PATCH] media: em28xx: fix v4l2 use-after-free after failed init and found the following issue: possible deadlock in em28xx_release_resources Full report is available here: https://ci.syzbot.org/series/92e27f7a-9ca9-4693-ad76-730262f6efd0 *** possible deadlock in em28xx_release_resources tree: torvalds URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux base: cbbddb6b08cc9900a87cccaa9b22bbe06aa4f50a arch: amd64 compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8 config: https://ci.syzbot.org/builds/5e867cfe-3c44-46f3-be9a-3394e10312c7/config syz repro: https://ci.syzbot.org/findings/de514af7-755a-455f-9075-91732cf09a76/syz_repro em28xx 1-1:1.0: Closing video extension em28xx 1-1:1.0: Closing input extension ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- kworker/0:3/5059 is trying to acquire lock: ffff88801cd25cf0 (&dev->lock#3){+.+.}-{4:4}, at: em28xx_release_resources+0x75/0x240 drivers/media/usb/em28xx/em28xx-cards.c:3796 but task is already holding lock: ffff88801cd25cf0 (&dev->lock#3){+.+.}-{4:4}, at: em28xx_v4l2_fini+0xb7/0x3f0 drivers/media/usb/em28xx/em28xx-video.c:2431 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&dev->lock#3); lock(&dev->lock#3); *** DEADLOCK *** May be due to missing lock nesting notation locks held by kworker/0:3/5059: 6, last CPU#0: #0: ffff8881032cb948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff8881032cb948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff8881032cb948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff8881032cb948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc900036cfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc900036cfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc900036cfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc900036cfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffff88816eeb71d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1109 [inline] #2: ffff88816eeb71d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5917 #3: ffff88801cdfc1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1109 [inline] #3: ffff88801cdfc1d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0 drivers/usb/core/hub.c:2346 #4: ffff88801ce5a1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1109 [inline] #4: ffff88801ce5a1a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1046 [inline] #4: ffff88801ce5a1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xa9/0x7d0 drivers/base/dd.c:1377 #5: ffff88801cd25cf0 (&dev->lock#3){+.+.}-{4:4}, at: em28xx_v4l2_fini+0xb7/0x3f0 drivers/media/usb/em28xx/em28xx-video.c:2431 stack backtrace: CPU: 0 UID: 0 PID: 5059 Comm: kworker/0:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Workqueue: usb_hub_wq hub_event Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x27a/0x290 kernel/locking/lockdep.c:3085 check_deadlock kernel/locking/lockdep.c:3137 [inline] validate_chain kernel/locking/lockdep.c:3939 [inline] __lock_acquire+0x25db/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821 em28xx_release_resources+0x75/0x240 drivers/media/usb/em28xx/em28xx-cards.c:3796 em28xx_usb_disconnect+0x19f/0x2f0 drivers/media/usb/em28xx/em28xx-cards.c:4493 usb_unbind_interface+0x295/0x9c0 drivers/usb/core/driver.c:460 device_remove drivers/base/dd.c:619 [inline] __device_release_driver drivers/base/dd.c:1357 [inline] device_release_driver_internal+0x48d/0x7d0 drivers/base/dd.c:1380 bus_remove_device+0x444/0x560 drivers/base/bus.c:678 device_del+0x524/0x8f0 drivers/base/core.c:3967 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1484 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2355 hub_port_connect drivers/usb/core/hub.c:5425 [inline] hub_port_connect_change drivers/usb/core/hub.c:5725 [inline] port_event drivers/usb/core/hub.c:5889 [inline] hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5971 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 *** If these findings have caused you to resend the series or submit a separate fix, please add the following tag to your commit message: Tested-by: syzbot@syzkaller.appspotmail.com --- This report is generated by a bot. It may contain errors. syzbot ci engineers can be reached at syzkaller@googlegroups.com. To test a fix for this bug, please reply with `#syz test` (on a separate line) and attach the patch to the email. Notes: - The patch will be applied on top of the tested series (as an incremental fix). - To test a new version of the whole series, please send it directly to syzbot@lists.linux.dev. - Arguments like custom git repos and branches are not supported. The email will later be sent to: [drifabdelmalekmohamedsaid@gmail.com hverkuil@kernel.org linux-kernel@vger.kernel.org linux-media@vger.kernel.org linux-usb@vger.kernel.org mchehab@kernel.org stable@vger.kernel.org syzbot@syzkaller.appspotmail.com] If the report looks fine to you, reply with: #syz upstream If the report is a false positive, reply with #syz invalid