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FKIE_CVE-2026-80810

Vulnerability from fkie_nvd - Published: 2026-09-04 16:18 - Updated: 2026-09-04 16:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring/rsrc: fix folio size overflow in io_vec_fill_bvec() io_vec_fill_bvec() computes the folio size with a plain int 1: unsigned long folio_size = 1 << imu->folio_shift; imu->folio_shift is unsigned int and comes from folio_shift() of the folio backing the registered buffer, so it can be 32 or more on a 64 bit kernel. Shifting int 1 that far is undefined, and on x86 and arm64 the count is taken modulo 32, so a shift of 34 yields 4 rather than 16G. Every other folio_shift shift in this file already uses 1UL. The result is that the segment estimate and the fill loop disagree. io_estimate_bvec_size() sizes the bvec array with the real shift: max_segs += (iov[i].iov_len >> shift) + 2; so a 1M iovec on a 16G folio is charged 2 segments, while io_vec_fill_bvec() then walks the same iovec in folio_size chunks of 4 bytes and writes res_bvec[bvec_idx] a quarter of a million times, past the end of the array it was given. src_bvec is advanced once per iteration as well, so imu->bvec is read past its end at the same time. validate_fixed_range() only checks that the range is inside the registered buffer and does not bound the segment count. Reaching it needs a folio with a shift of at least 32, which means a gigantic hugetlb page: 16G on arm64 with 64K pages, where CONT_PMD_SHIFT is 34 and hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT) registers that size, and likewise on powerpc. x86_64 tops out at 1G, so a shift of 30, which still fits in int and is unaffected. Use 1UL, as the rest of the file does.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3267d7c8ba51642117f7bdd1ece02b2540668476
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3f3a6a16bbe8bde76532d9415438f8cdef439e5d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/45c945107e007b1fb73e21cd220277652a45521a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6b308c37fbeba3aa8c634fb1ed53e2f63a5d5a5c
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/rsrc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "45c945107e007b1fb73e21cd220277652a45521a",
              "status": "affected",
              "version": "9ef4cbbcb4ac3786a1a4164507511b76b2a572c5",
              "versionType": "git"
            },
            {
              "lessThan": "6b308c37fbeba3aa8c634fb1ed53e2f63a5d5a5c",
              "status": "affected",
              "version": "9ef4cbbcb4ac3786a1a4164507511b76b2a572c5",
              "versionType": "git"
            },
            {
              "lessThan": "3267d7c8ba51642117f7bdd1ece02b2540668476",
              "status": "affected",
              "version": "9ef4cbbcb4ac3786a1a4164507511b76b2a572c5",
              "versionType": "git"
            },
            {
              "lessThan": "3f3a6a16bbe8bde76532d9415438f8cdef439e5d",
              "status": "affected",
              "version": "9ef4cbbcb4ac3786a1a4164507511b76b2a572c5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/rsrc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.47",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.1",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/rsrc: fix folio size overflow in io_vec_fill_bvec()\n\nio_vec_fill_bvec() computes the folio size with a plain int 1:\n\n\tunsigned long folio_size = 1 \u003c\u003c imu-\u003efolio_shift;\n\nimu-\u003efolio_shift is unsigned int and comes from folio_shift() of the\nfolio backing the registered buffer, so it can be 32 or more on a 64 bit\nkernel. Shifting int 1 that far is undefined, and on x86 and arm64 the\ncount is taken modulo 32, so a shift of 34 yields 4 rather than 16G.\nEvery other folio_shift shift in this file already uses 1UL.\n\nThe result is that the segment estimate and the fill loop disagree.\nio_estimate_bvec_size() sizes the bvec array with the real shift:\n\n\tmax_segs += (iov[i].iov_len \u003e\u003e shift) + 2;\n\nso a 1M iovec on a 16G folio is charged 2 segments, while\nio_vec_fill_bvec() then walks the same iovec in folio_size chunks of 4\nbytes and writes res_bvec[bvec_idx] a quarter of a million times, past\nthe end of the array it was given. src_bvec is advanced once per\niteration as well, so imu-\u003ebvec is read past its end at the same time.\nvalidate_fixed_range() only checks that the range is inside the\nregistered buffer and does not bound the segment count.\n\nReaching it needs a folio with a shift of at least 32, which means a\ngigantic hugetlb page: 16G on arm64 with 64K pages, where\nCONT_PMD_SHIFT is 34 and hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT)\nregisters that size, and likewise on powerpc. x86_64 tops out at 1G, so\na shift of 30, which still fits in int and is unaffected.\n\nUse 1UL, as the rest of the file does."
    }
  ],
  "id": "CVE-2026-80810",
  "lastModified": "2026-09-04T16:18:08.360",
  "metrics": {},
  "published": "2026-09-04T16:18:08.360",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3267d7c8ba51642117f7bdd1ece02b2540668476"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3f3a6a16bbe8bde76532d9415438f8cdef439e5d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/45c945107e007b1fb73e21cd220277652a45521a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6b308c37fbeba3aa8c634fb1ed53e2f63a5d5a5c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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