CVE-2026-98836 (GCVE-0-2026-98836)
Vulnerability from cvelistv5
Published
2026-10-18 15:49
Modified
2026-10-21 12:57
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: line6: reject oversized playback packets Each playback URB is handed a slice of out.buffer that is exactly LINE6_ISO_PACKETS * max_packet_size_out bytes, sized from the OUT endpoint, but the number of bytes written into that slice is never compared against it. submit_audio_out_urb() takes the frame count from prev_fsize, which audio_in_callback() derived from the *IN* endpoint's received packet length, and rescales it with the playback frame size; when prev_fsize is still zero it synthesizes a length from the sample rate instead. On a device declaring a large IN wMaxPacketSize and a small OUT wMaxPacketSize, the resulting memcpy(), or the memset() when the playback stream is idle, runs past its slice and, as the reproducer below shows, beyond the allocation. usb_submit_urb() is not a backstop. max_packet_size_out comes from usb_maxpacket(), which returns only the low 11 bits of wMaxPacketSize, while USB core validates a high-speed isochronous length against that base scaled by usb_endpoint_maxp_mult(). A length of up to three times the allocated slice is therefore accepted, and even a rejected URB is only rejected after the write. Reject a packet that does not fit the slice the driver allocated for it. Clamping it instead would silently shorten the capture-derived rate feedback and desynchronize the two streams. BUG: KASAN: slab-out-of-bounds in submit_audio_out_urb (sound/usb/line6/playback.c:229) Write of size 1024 at addr ffff888100bbd400 by task kworker/1:2/5002 Workqueue: events line6_startup_work Call Trace: __asan_memcpy (mm/kasan/shadow.c:106) submit_audio_out_urb (sound/usb/line6/playback.c:229) line6_submit_audio_out_all_urbs (sound/usb/line6/playback.c:291) line6_stream_start (sound/usb/line6/pcm.c:194) line6_pcm_acquire (sound/usb/line6/pcm.c:337) line6_startup_work (sound/usb/line6/driver.c:728) process_one_work (kernel/workqueue.c:3396) worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) ret_from_fork_asm (arch/x86/entry/entry_64.S:245) The buggy address belongs to the object at ffff888100bbd400 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 0 bytes inside of allocated 256-byte region [ffff888100bbd400, ffff888100bbd500)
References
Impacted products
Vendor Product Version
Linux Linux Version: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692
Version: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692
Version: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692
Version: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692
Version: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/usb/line6/playback.c"
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          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "6.12.113",
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              "lessThanOrEqual": "6.18.*",
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              "version": "6.18.56",
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              "version": "7.2.10",
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            },
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u0027s 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)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:57:22.028Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/933d8ac23388eb208ea195231d682dce0bec86ca"
        },
        {
          "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"
        }
      ],
      "title": "ALSA: line6: reject oversized playback packets",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98836",
    "datePublished": "2026-10-18T15:49:51.823Z",
    "dateReserved": "2026-09-25T10:25:14.372Z",
    "dateUpdated": "2026-10-21T12:57:22.028Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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