ghsa-q3h4-pxwf-237f
Vulnerability from github
Published
2024-06-21 12:31
Modified
2024-06-27 15:30
Details

In the Linux kernel, the following vulnerability has been resolved:

media: stk1160: fix bounds checking in stk1160_copy_video()

The subtract in this condition is reversed. The ->length is the length of the buffer. The ->bytesused is how many bytes we have copied thus far. When the condition is reversed that means the result of the subtraction is always negative but since it's unsigned then the result is a very high positive value. That means the overflow check is never true.

Additionally, the ->bytesused doesn't actually work for this purpose because we're not writing to "buf->mem + buf->bytesused". Instead, the math to calculate the destination where we are writing is a bit involved. You calculate the number of full lines already written, multiply by two, skip a line if necessary so that we start on an odd numbered line, and add the offset into the line.

To fix this buffer overflow, just take the actual destination where we are writing, if the offset is already out of bounds print an error and return. Otherwise, write up to buf->length bytes.

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{
  "affected": [],
  "aliases": [
    "CVE-2024-38621"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-06-21T11:15:11Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: stk1160: fix bounds checking in stk1160_copy_video()\n\nThe subtract in this condition is reversed.  The -\u003elength is the length\nof the buffer.  The -\u003ebytesused is how many bytes we have copied thus\nfar.  When the condition is reversed that means the result of the\nsubtraction is always negative but since it\u0027s unsigned then the result\nis a very high positive value.  That means the overflow check is never\ntrue.\n\nAdditionally, the -\u003ebytesused doesn\u0027t actually work for this purpose\nbecause we\u0027re not writing to \"buf-\u003emem + buf-\u003ebytesused\".  Instead, the\nmath to calculate the destination where we are writing is a bit\ninvolved.  You calculate the number of full lines already written,\nmultiply by two, skip a line if necessary so that we start on an odd\nnumbered line, and add the offset into the line.\n\nTo fix this buffer overflow, just take the actual destination where we\nare writing, if the offset is already out of bounds print an error and\nreturn.  Otherwise, write up to buf-\u003elength bytes.",
  "id": "GHSA-q3h4-pxwf-237f",
  "modified": "2024-06-27T15:30:40Z",
  "published": "2024-06-21T12:31:20Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-38621"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7532bcec0797adfa08791301c3bcae14141db3bd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a08492832cc4cacc24e0612f483c86ca899b9261"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a16775828aaed1c54ff4e6fe83e8e4d5c6a50cb7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b504518a397059e1d55c521ba0ea2b545a6c4b52"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d410017a7181cb55e4a5c810b32b75e4416c6808"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ecf4ddc3aee8ade504c4d36b7b4053ce6093e200"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f6a392266276730bea893b55d12940e32a25f56a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/faa4364bef2ec0060de381ff028d1d836600a381"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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