CVE-2026-89901 media: airspy: use vb2_video_unregister_device() on disconnect to fix NULL deref
A NULL pointer dereference in the Linux kernel airspy driver allows local attackers to cause a system crash by disconnecting the device during streaming.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89901?
CVE-2026-89901 is a vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
media: airspy: use vb2_video_unregister_device() on disconnect to fix NULL deref
airspy_disconnect() clears s->udev under v4l2_lock, but airspy_stop_streaming() unconditionally calls airspy_ctrl_msg() and airspy_free_stream_bufs() afterwards. If a streaming user closes the device after disconnect, stop_streaming() runs and dereferences the NULL s->udev:
airspy_stop_streaming() airspy_ctrl_msg(s, CMD_RECEIVER_MODE, 0, 0, NULL, 0) usb_sndctrlpipe(s->udev, 0) /* NULL deref */ airspy_free_stream_bufs(s) usb_free_coherent(s->udev, ...) /* NULL deref */
The airspy driver uses vb2_fop_release() in its file_operations, so replace video_unregister_device(&s->vdev) with vb2_video_unregister_device(&s->vdev) and move it before clearing s->udev. vb2_video_unregister_device() releases the vb2 queue, which synchronously runs airspy_stop_streaming() if streaming is active, so the URBs, coherent DMA stream buffers and the hardware stop control message all execute while s->udev is still valid.
vb2_video_unregister_device() locks vdev->queue->lock (vb_queue_lock) internally, and stop_streaming() locks v4l2_lock, so the previous outer mutex_lock(&s->vb_queue_lock) / mutex_lock(&s->v4l2_lock) pair around the unregister sequence would self-deadlock and has been removed. A short v4l2_lock critical section around s->udev = NULL remains so any ioctl path that still holds the file descriptor sees coherent state.
Issue identified by automated review of the INV-003 series at https://sashiko.dev/
Which versions are affected by CVE-2026-89901?
How do I fix CVE-2026-89901?
Apply the vendor's patch.
Is CVE-2026-89901 being exploited?
There is no known exploitation of CVE-2026-89901 in the wild and no public exploit code.
Sources
Also known as AZL-101231, BELL-CVE-2026-89901, DEBIAN-CVE-2026-89901, GHSA-wfp4-jcv3-wqgx, UBUNTU-CVE-2026-89901.