{"id":"CVE-2026-98836","title":"ALSA: line6: reject oversized playback packets","summary":"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 f…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < a84371be89c39ccc46c7af8b9eb15c448df9265f","Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < 3f75da1e4ee699f6650d23d6897cf443b01856c7","Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < b78748424f29f07d310484b2b36afdececa74389","Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < 61b0a5a114fa4552892da5c0ff2f42e63bf08c6b","Linux 4.9"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:49:51.823Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98836","references":[{"url":"https://git.kernel.org/stable/c/a84371be89c39ccc46c7af8b9eb15c448df9265f"},{"url":"https://git.kernel.org/stable/c/3f75da1e4ee699f6650d23d6897cf443b01856c7"},{"url":"https://git.kernel.org/stable/c/b78748424f29f07d310484b2b36afdececa74389"},{"url":"https://git.kernel.org/stable/c/61b0a5a114fa4552892da5c0ff2f42e63bf08c6b"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.468Z","slug":"CVE-2026-98836","body":"## Overview\n\nIn 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)\n\n## Affected\n\n- `Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < a84371be89c39ccc46c7af8b9eb15c448df9265f`\n- `Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < 3f75da1e4ee699f6650d23d6897cf443b01856c7`\n- `Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < b78748424f29f07d310484b2b36afdececa74389`\n- `Linux >= 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 < 61b0a5a114fa4552892da5c0ff2f42e63bf08c6b`\n- `Linux 4.9`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}