{"id":"CVE-2026-89881","published":"2026-09-16T11:16:56.503","lastModified":"2026-09-16T11:16:56.503","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: rtl2832_sdr: use vb2_video_unregister_device() on remove to fix DMA leak\n\nrtl2832_sdr_remove() runs on USB disconnect and clears dev->udev to\nNULL before any pending streaming teardown has run. When user space\nlater closes its file descriptor, vb2 calls rtl2832_sdr_stop_streaming()\nwhich in turn calls rtl2832_sdr_free_stream_bufs(). That helper releases\neach coherent buffer with:\n\n    usb_free_coherent(dev->udev, dev->buf_size,\n                      dev->buf_list[dev->buf_num],\n                      dev->dma_addr[dev->buf_num]);\n\nusb_free_coherent() returns immediately when its dev argument is NULL,\nso every DMA stream buffer that was live at disconnect is silently\nleaked. The URBs allocated in rtl2832_sdr_alloc_urbs() outlive the\ndevice for the same reason.\n\nThe rtl2832_sdr driver uses vb2_fop_release() in its file_operations,\nso replace video_unregister_device(&dev->vdev) with\nvb2_video_unregister_device(&dev->vdev) and move it before clearing\ndev->udev. vb2_video_unregister_device() releases the vb2 queue, which\nsynchronously runs rtl2832_sdr_stop_streaming() if streaming is active,\nso URBs and coherent DMA stream buffers are freed while dev->udev is\nstill valid.\n\nvb2_video_unregister_device() locks vdev->queue->lock (vb_queue_lock)\ninternally, and stop_streaming() locks v4l2_lock, so the previous outer\nmutex_lock(&dev->vb_queue_lock) / mutex_lock(&dev->v4l2_lock) pair\naround the unregister sequence would self-deadlock and has been removed.\nA short v4l2_lock critical section around dev->udev = NULL remains so\nany ioctl path that still holds the file descriptor sees coherent state.\n\nIssue identified by automated review of the INV-003 series at\nhttps://sashiko.dev/","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/034b6a4f9589c04bc3f2bd5125658cd72d3e17c8","tags":[]},{"url":"https://git.kernel.org/stable/c/053581d4657c6b5289c5de71a4828d313c005189","tags":[]},{"url":"https://git.kernel.org/stable/c/0ef9f19010ae4ba93aca211ea8f0081b9bf7aab2","tags":[]},{"url":"https://git.kernel.org/stable/c/234c46b95a032232e31fa5987b84fb8f87a9693b","tags":[]},{"url":"https://git.kernel.org/stable/c/7443b16b6dd8889a3b9c5236a09e7c58f0d11dae","tags":[]},{"url":"https://git.kernel.org/stable/c/a0d9d9a3b41a1346c26af57aade6ba3f552fa171","tags":[]},{"url":"https://git.kernel.org/stable/c/bbf15e83c37d9ac938b7c35c02b748fe54230010","tags":[]},{"url":"https://git.kernel.org/stable/c/dabb047c62668f280998e29117c55e41aabac336","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}