{"id":"AZL-101550","summary":"CVE-2026-89881 affecting package kernel 6.6.150.1-1","details":"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-\u003eudev 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-\u003eudev, dev-\u003ebuf_size,\n                      dev-\u003ebuf_list[dev-\u003ebuf_num],\n                      dev-\u003edma_addr[dev-\u003ebuf_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-\u003evdev) with\nvb2_video_unregister_device(&dev-\u003evdev) and move it before clearing\ndev-\u003eudev. 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-\u003eudev is\nstill valid.\n\nvb2_video_unregister_device() locks vdev-\u003equeue-\u003elock (vb_queue_lock)\ninternally, and stop_streaming() locks v4l2_lock, so the previous outer\nmutex_lock(&dev-\u003evb_queue_lock) / mutex_lock(&dev-\u003ev4l2_lock) pair\naround the unregister sequence would self-deadlock and has been removed.\nA short v4l2_lock critical section around dev-\u003eudev = 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/","modified":"2026-09-19T05:33:49Z","published":"2026-09-16T11:16:56Z","upstream":["CVE-2026-89881"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89881"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-101550.json"}}],"schema_version":"1.9.0"}