FKIE_CVE-2026-90117

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-17 17:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs: validate usa_ofs before preserving the update sequence number When ntfs_mft_record_alloc() reuses a free mft record it reads the old update sequence number straight from the on-disk record: usn = *(__le16 *)((u8 *)m + le16_to_cpu(m->usa_ofs)); Here m points into the raw $MFT page-cache folio, which still holds unvalidated, MST-protected bytes: the folio is read by a plain iomap_read_folio() and neither post_read_mst_fixup() nor ntfs_mft_record_check() has run on it (both work on private copies). m->usa_ofs is therefore an untrusted u16, and a corrupted record can put it past the end of the record so the two-byte read lands outside the folio. Reading such a record while creating a file gives, under KASAN: BUG: KASAN: use-after-free in ntfs_mft_record_alloc+... Read of size 2 at addr ... ntfs_mft_record_alloc -> __ntfs_create -> ntfs_create -> path_openat Only preserve the old update sequence number when usa_ofs is even and in range, mirroring the check ntfs_mft_record_check() already applies; otherwise leave usn zero, which the existing restore below skips.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/81684340963da2e898eabb8c1e274433d9375bc6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ea5a3c30710710c1dc5e483d3313309ec2e868f7
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/mft.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ea5a3c30710710c1dc5e483d3313309ec2e868f7",
              "status": "affected",
              "version": "495e90fa334828d4119061e2726af51d0a0fb4ed",
              "versionType": "git"
            },
            {
              "lessThan": "81684340963da2e898eabb8c1e274433d9375bc6",
              "status": "affected",
              "version": "495e90fa334828d4119061e2726af51d0a0fb4ed",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/mft.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "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\nntfs: validate usa_ofs before preserving the update sequence number\n\nWhen ntfs_mft_record_alloc() reuses a free mft record it reads the old\nupdate sequence number straight from the on-disk record:\n\n     usn = *(__le16 *)((u8 *)m + le16_to_cpu(m-\u003eusa_ofs));\n\nHere m points into the raw $MFT page-cache folio, which still holds\nunvalidated, MST-protected bytes: the folio is read by a plain\niomap_read_folio() and neither post_read_mst_fixup() nor\nntfs_mft_record_check() has run on it (both work on private copies).\nm-\u003eusa_ofs is therefore an untrusted u16, and a corrupted record can put\nit past the end of the record so the two-byte read lands outside the\nfolio.  Reading such a record while creating a file gives, under KASAN:\n\n   BUG: KASAN: use-after-free in ntfs_mft_record_alloc+...\n   Read of size 2 at addr ...\n    ntfs_mft_record_alloc -\u003e __ntfs_create -\u003e ntfs_create -\u003e path_openat\n\nOnly preserve the old update sequence number when usa_ofs is even and in\nrange, mirroring the check ntfs_mft_record_check() already applies;\notherwise leave usn zero, which the existing restore below skips."
    }
  ],
  "id": "CVE-2026-90117",
  "lastModified": "2026-09-17T17:17:03.857",
  "metrics": {},
  "published": "2026-09-17T17:17:03.857",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/81684340963da2e898eabb8c1e274433d9375bc6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ea5a3c30710710c1dc5e483d3313309ec2e868f7"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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