{"schema":"threatline.record/2","record":{"id":"CVE-2026-98836","aliases":[],"summary":"ALSA: line6: reject oversized playback packets","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: line6: reject oversized playback packets\n\nEach playback URB is handed a slice of out.buffer that is exactly\nLINE6_ISO_PACKETS * max_packet_size_out bytes, sized from the OUT\nendpoint, but the number of bytes written into that slice is never\ncompared against it.\n\nsubmit_audio_out_urb() takes the frame count from prev_fsize, which\naudio_in_callback() derived from the *IN* endpoint's received packet\nlength, and rescales it with the playback frame size; when prev_fsize is\nstill zero it synthesizes a length from the sample rate instead.  On a\ndevice declaring a large IN wMaxPacketSize and a small OUT\nwMaxPacketSize, the resulting memcpy(), or the memset() when the\nplayback stream is idle, runs past its slice and, as the reproducer\nbelow shows, beyond the allocation.\n\nusb_submit_urb() is not a backstop.  max_packet_size_out comes from\nusb_maxpacket(), which returns only the low 11 bits of wMaxPacketSize,\nwhile USB core validates a high-speed isochronous length against that\nbase scaled by usb_endpoint_maxp_mult().  A length of up to three times\nthe allocated slice is therefore accepted, and even a rejected URB is\nonly rejected after the write.\n\nReject a packet that does not fit the slice the driver allocated for it.\nClamping it instead would silently shorten the capture-derived rate\nfeedback and desynchronize the two streams.\n\n  BUG: KASAN: slab-out-of-bounds in submit_audio_out_urb (sound/usb/line6/playback.c:229)\n  Write of size 1024 at addr ffff888100bbd400 by task kworker/1:2/5002\n  Workqueue: events line6_startup_work\n  Call Trace:\n   __asan_memcpy (mm/kasan/shadow.c:106)\n   submit_audio_out_urb (sound/usb/line6/playback.c:229)\n   line6_submit_audio_out_all_urbs (sound/usb/line6/playback.c:291)\n   line6_stream_start (sound/usb/line6/pcm.c:194)\n   line6_pcm_acquire (sound/usb/line6/pcm.c:337)\n   line6_startup_work (sound/usb/line6/driver.c:728)\n   process_one_work (kernel/workqueue.c:3396)\n   worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560)\n   kthread (kernel/kthread.c:436)\n   ret_from_fork (arch/x86/kernel/process.c:158)\n   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n\n  The buggy address belongs to the object at ffff888100bbd400\n   which belongs to the cache kmalloc-256 of size 256\n  The buggy address is located 0 bytes inside of\n   allocated 256-byte region [ffff888100bbd400, ffff888100bbd500)","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98836","source_modified_at":"2026-10-21T12:57:22.028Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"7a0f55aeeb8f1fa32a119d34ddfefc6100936692","lessThan":"933d8ac23388eb208ea195231d682dce0bec86ca","status":"affected","versionType":"git"},{"version":"7a0f55aeeb8f1fa32a119d34ddfefc6100936692","lessThan":"a84371be89c39ccc46c7af8b9eb15c448df9265f","status":"affected","versionType":"git"},{"version":"7a0f55aeeb8f1fa32a119d34ddfefc6100936692","lessThan":"3f75da1e4ee699f6650d23d6897cf443b01856c7","status":"affected","versionType":"git"},{"version":"7a0f55aeeb8f1fa32a119d34ddfefc6100936692","lessThan":"b78748424f29f07d310484b2b36afdececa74389","status":"affected","versionType":"git"},{"version":"7a0f55aeeb8f1fa32a119d34ddfefc6100936692","lessThan":"61b0a5a114fa4552892da5c0ff2f42e63bf08c6b","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98836","source_modified_at":"2026-10-21T12:57:22.028Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"4.9","status":"affected"},{"version":"0","lessThan":"4.9","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.113","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.56","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.10","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98836","source_modified_at":"2026-10-21T12:57:22.028Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"933d8ac23388eb208ea195231d682dce0bec86ca","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98836","source_modified_at":"2026-10-21T12:57:22.028Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"3f75da1e4ee699f6650d23d6897cf443b01856c7","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98836","source_modified_at":"2026-10-21T12:57:22.028Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"61b0a5a114fa4552892da5c0ff2f42e63bf08c6b","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00168,"percentile":0.05749,"score_date":"2026-10-23"},"published_at":"2026-10-18T15:49:51.823Z","modified_at":"2026-10-21T12:57:22.028Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98836","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-21T12:57:22.028Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98836","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/933d8ac23388eb208ea195231d682dce0bec86ca"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/a84371be89c39ccc46c7af8b9eb15c448df9265f"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/3f75da1e4ee699f6650d23d6897cf443b01856c7"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/b78748424f29f07d310484b2b36afdececa74389"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/61b0a5a114fa4552892da5c0ff2f42e63bf08c6b"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-21T12:57:22.028Z","content_hash":"9fd0f745a146c6edcc81dc14e3aa7048a573a1027d9e17d92bf399ca776c5b19"}}