* [moderation/CI] Re: media: em28xx: fix v4l2 use-after-free after failed init
@ 2026-11-01 16:37 syzbot ci
2026-11-01 21:13 ` Aleksandr Nogikh
0 siblings, 1 reply; 2+ messages in thread
From: syzbot ci @ 2026-11-01 16:37 UTC (permalink / raw)
To: syzkaller-upstream-moderation; +Cc: syzbot
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:
<TASK>
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
</TASK>
***
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [moderation/CI] Re: media: em28xx: fix v4l2 use-after-free after failed init
2026-11-01 16:37 [moderation/CI] Re: media: em28xx: fix v4l2 use-after-free after failed init syzbot ci
@ 2026-11-01 21:13 ` Aleksandr Nogikh
0 siblings, 0 replies; 2+ messages in thread
From: Aleksandr Nogikh @ 2026-11-01 21:13 UTC (permalink / raw)
To: syzbot ci; +Cc: syzkaller-upstream-moderation, syzbot
#syz upstream
On Sun, Nov 1, 2026 at 5:37 PM syzbot ci
<syzbot+ciedcd9b7e9104cbc7@syzkaller.appspotmail.com> wrote:
>
> 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:
> <TASK>
> 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
> </TASK>
>
>
> ***
>
> 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
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-upstream-moderation" group.
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^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-11-01 21:13 UTC | newest]
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2026-11-01 16:37 [moderation/CI] Re: media: em28xx: fix v4l2 use-after-free after failed init syzbot ci
2026-11-01 21:13 ` Aleksandr Nogikh
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