{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-31602",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-31602"
  ],
  "published": "2026-04-24T14:43:40Z",
  "summary": "ALSA: ctxfi: Limit PTP to a single page",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: ctxfi: Limit PTP to a single page\n\nCommit 391e69143d0a increased CT_PTP_NUM from 1 to 4 to support 256\nplayback streams, but the additional pages are not used by the card\ncorrectly. The CT20K2 hardware already has multiple VMEM_PTPAL\nregisters, but using them separately would require refactoring the\nentire virtual memory allocation logic.\n\nct_vm_map() always uses PTEs in vm->ptp[0].area regardless of\nCT_PTP_NUM. On AMD64 systems, a single PTP covers 512 PTEs (2M). When\naggregate memory allocations exceed this limit, ct_vm_map() tries to\naccess beyond the allocated space and causes a page fault:\n\n  BUG: unable to handle page fault for address: ffffd4ae8a10a000\n  Oops: Oops: 0002 [#1] SMP PTI\n  RIP: 0010:ct_vm_map+0x17c/0x280 [snd_ctxfi]\n  Call Trace:\n  atc_pcm_playback_prepare+0x225/0x3b0\n  ct_pcm_playback_prepare+0x38/0x60\n  snd_pcm_do_prepare+0x2f/0x50\n  snd_pcm_action_single+0x36/0x90\n  snd_pcm_action_nonatomic+0xbf/0xd0\n  snd_pcm_ioctl+0x28/0x40\n  __x64_sys_ioctl+0x97/0xe0\n  do_syscall_64+0x81/0x610\n  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nRevert CT_PTP_NUM to 1. The 256 SRC_RESOURCE_NUM and playback_count\nremain unchanged.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.175",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-31602"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c5908160e17cb56e1f61fbaee08adc21083f4933"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/de8016fb0904d68ac886e375069535996baa42ee"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2b4331c08c0b385598b4d8ccd71e93ab3f4b2578"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/452894005b4abe141b11fe01e7bfe152e6d3860f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/365c36e1a126c6aa1aecedd3a351bcabc66f0c29"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3fd0685d7fef68c2d8a04876bcf9eaa0724ad6a5"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b7f5ecd13cce8c2f8fa5a84c9aab65997142577e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ad9011a795407093dcf507f6e5da1828987b4b47"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e9418da50d9e5c496c22fe392e4ad74c038a94eb"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z"
  }
}