{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-98265",
  "modified": "2026-10-07T14:35:31Z",
  "upstream": [
    "CVE-2026-98265"
  ],
  "published": "2026-10-06T08:47:10Z",
  "summary": "ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: Clamp implicit feedback packet count to URB capacity\n\ndata_ep_set_params() allocates each data URB for exactly u->packets\nisochronous frames, so urb->iso_frame_desc[] has u->packets slots and\nctx->packets is the driver's only record of that limit. For an implicit\nfeedback sink, snd_usb_queue_pending_output_urbs() overwrites it with the\nsync source's packet count, which is calculated independently from the\ncapture endpoint's parameters. When that count is larger,\nprepare_playback_urb() and prepare_silent_urb() can write\niso_frame_desc[] past the allocation; their existing bounds limit payload\nbytes, not the descriptor index.\n\nThe reproducer uses a high-speed UAC2 device declaring bInterval 1 for\nimplicit feedback capture (8 packets) and bInterval 4 for playback\n(1 packet). On the first capture completion after the stream starts, it\naccesses seven descriptors spanning 112 bytes beyond the one-packet URB:\n\n  BUG: KASAN: slab-out-of-bounds in prepare_playback_urb (sound/usb/pcm.c:1560)\n  Write of size 4 at addr ffff88801e696ad0 by task vhci_rx/178\n   prepare_playback_urb (sound/usb/pcm.c:1560)\n   prepare_outbound_urb (sound/usb/endpoint.c:340)\n   snd_usb_queue_pending_output_urbs (sound/usb/endpoint.c:501)\n   snd_complete_urb (sound/usb/endpoint.c:1834)\n   __usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1657)\n   usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1741)\n   vhci_rx_loop (drivers/usb/usbip/vhci_rx.c:107)\n   kthread (kernel/kthread.c:436)\n  The buggy address belongs to the object at ffff88801e696a00\n   which belongs to the cache kmalloc-256 of size 256\n  The buggy address is located 0 bytes to the right of\n   allocated 208-byte region [ffff88801e696a00, ffff88801e696ad0)\n\nRecord the allocated packet count per endpoint and clamp both the adopted\ncount and the packet-size copy to it. Fold the Format Type II delimiter\ninto urb_packs before the allocation loop so the recorded limit matches\nevery URB.",
  "affected": [
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        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
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        "1:6.12.93-1+rpt1",
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-98265"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ad279ba0dc1781229f5b52f58d38d56960400e06"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/79c55a7b5d71cf2a6bbd4bd7698e1b10b70f813a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ab77e3f453c5f2499c08d6e8e218501d25bab39e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/76a986c980bb502c7688d605ac7a67fd257a9a1b"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-10-06T08:47:10Z"
  }
}