CVE Catalog

CVE-2026-89881

Low risk· EPSS 11%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.21%

11th percentile - higher than 11% of all known CVEs

Summary

In the Linux kernel, the rtl2832_sdr media driver has a DMA memory leak. On USB disconnect, rtl2832_sdr_remove() sets dev->udev to NULL before streaming teardown completes, so usb_free_coherent() fails to release DMA buffers and allocated URBs outlive the device. The fix replaces video_unregister_device() with vb2_video_unregister_device() called before clearing dev->udev.

Risk Assessment

Leaking DMA buffers and URBs on every USB disconnect of an affected device can gradually exhaust kernel memory and cause system instability, especially on hosts where such devices are repeatedly plugged and unplugged.

Recommendation

Update the Linux kernel to a version containing the fix for CVE-2026-89881 (the commit replacing video_unregister_device() with vb2_video_unregister_device() in the rtl2832_sdr driver). Until patched, avoid frequent disconnects of RTL2832U-based devices during active streaming.

Related vulnerabilities

Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: media: rtl2832_sdr: use vb2_video_unregister_device() on remove to fix DMA leak rtl2832_sdr_remove() runs on USB disconnect and clears dev->udev to NULL before any pending streaming teardown has run. When user space later closes its file descriptor, vb2 calls rtl2832_sdr_stop_streaming() which in turn calls rtl2832_sdr_free_stream_bufs(). That helper releases each coherent buffer with: usb_free_coherent(dev->udev, dev->buf_size, dev->buf_list[dev->buf_num], dev->dma_addr[dev->buf_num]); usb_free_coherent() returns immediately when its dev argument is NULL, so every DMA stream buffer that was live at disconnect is silently leaked. The URBs allocated in rtl2832_sdr_alloc_urbs() outlive the device for the same reason. The rtl2832_sdr driver uses vb2_fop_release() in its file_operations, so replace video_unregister_device(&dev->vdev) with vb2_video_unregister_device(&dev->vdev) and move it before clearing dev->udev. vb2_video_unregister_device() releases the vb2 queue, which synchronously runs rtl2832_sdr_stop_streaming() if streaming is active, so URBs and coherent DMA stream buffers are freed while dev->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(&dev->vb_queue_lock) / mutex_lock(&dev->v4l2_lock) pair around the unregister sequence would self-deadlock and has been removed. A short v4l2_lock critical section around dev->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/

Vulnerability data from NVD (NIST) · CISA KEV · EPSS