{"id":"CVE-2026-80971","summary":"ALSA: bcd2000: clear the URB pointers on disconnect","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: bcd2000: clear the URB pointers on disconnect\n\nbcd2000_free_usb_related_resources() frees both URBs and leaves the\npointers behind:\n\n\tusb_kill_urb(bcd2k-\u003emidi_out_urb);\n\tusb_kill_urb(bcd2k-\u003emidi_in_urb);\n\n\tusb_free_urb(bcd2k-\u003emidi_out_urb);\n\tusb_free_urb(bcd2k-\u003emidi_in_urb);\n\nThe rawmidi device outlives that call.  A substream that is still open\nwhen the device is unplugged reaches bcd2000_midi_send() from the\ntrigger path on close.  That function writes to the freed URB and then\nhands it to the USB core:\n\n\tbcd2k-\u003emidi_out_urb-\u003etransfer_buffer_length = BUFSIZE;\n\t...\n\tret = usb_submit_urb(bcd2k-\u003emidi_out_urb, GFP_ATOMIC);\n\nusb_kill_urb() does not stop a later submission either, so a submit that\nraces the disconnect can requeue the URB after it has been reaped.\nmidi_in_urb is exposed the same way: bcd2000_input_complete() resubmits\nit from the completion handler.\n\nKASAN on 7.2.0-rc5 (arm64):\n\n  BUG: KASAN: slab-use-after-free in bcd2000_midi_send [snd_bcd2000]\n  Write of size 4 at addr ffff00001827d388 by task bpoc/168\n   __asan_store4\n   bcd2000_midi_send [snd_bcd2000]\n   bcd2000_midi_output_trigger [snd_bcd2000]\n   snd_rawmidi_kernel_write1\n   close_substream.part.0\n  Freed by task 168:\n   usb_free_urb\n   bcd2000_disconnect [snd_bcd2000]\n\n  BUG: KASAN: slab-use-after-free in usb_submit_urb\n  Read of size 8 at addr ffff00001827d3b8 by task bpoc/168\n\nClear both pointers after freeing and test them on the paths that can\nstill run.  Poison the URBs before freeing them: usb_poison_urb() waits\nfor a running completion handler and rejects any later submission, so\nafter it returns the input path is quiesced and only the rawmidi trigger\npath can still reach bcd2000_midi_send().  No unpoison is needed; the\nURBs are freed on the next line.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e","modified":"2026-09-13T03:46:59.120834596Z","published":"2026-09-11T19:42:34.441Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80971.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/459d3a64766f5ca2f1886daeaf24582831a5f5ab"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7df3194bdb7479cad9199889655a566a2c0c1d1b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b06ebc7fe25a6af4a9f6e4a3d4236a4178ad4b01"},{"type":"WEB","url":"https://git.kernel.org/stable/c/eb482a06791d6168beb8c78cc904ac5a5ed96a55"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80971.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80971"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b47a22290d581277be70e8a597824a4985d39e83"},{"fixed":"eb482a06791d6168beb8c78cc904ac5a5ed96a55"},{"fixed":"7df3194bdb7479cad9199889655a566a2c0c1d1b"},{"fixed":"b06ebc7fe25a6af4a9f6e4a3d4236a4178ad4b01"},{"fixed":"459d3a64766f5ca2f1886daeaf24582831a5f5ab"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80971.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.16.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80971.json"}}],"schema_version":"1.9.0"}