CVE-2026-90096 (GCVE-0-2026-90096)
Vulnerability from cvelistv5
Published
2026-09-17 16:06
Modified
2026-10-19 08:57
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: fuse: invalidate the correct range after O_APPEND direct write fuse_direct_write_iter() captures pos before generic_write_checks(), which moves ki_pos to EOF for O_APPEND writes: fuse_direct_write_iter() { pos = iocb->ki_pos; /* 0 (user-supplied) */ generic_write_checks(); /* ki_pos -> EOF */ fuse_direct_io(); /* writes at EOF, correct */ invalidate(pos, pos + res); /* [0, res) -- wrong */ } The post-write invalidation targets a stale range instead of the actual written range at EOF. This can cause data inconsistency when the file size is not page-aligned. The tail page straddling EOF has a valid portion before EOF that concurrent readers can fault back in during the DIO write window: Tail page (file size X not page-aligned): page_start X (EOF) page_end |--- valid data ----|-- stale --| CPU0 (O_APPEND DIO writer) CPU1 (buffered reader) -------------------------- ---------------------- invalidate [X, X+len) tail page evicted FUSE_WRITE in flight ... read [page_start, X) tail page re-faulted [X, page_end) = stale FUSE_WRITE completes i_size = X + len invalidate [0, len) <- WRONG tail page still cached read [X, X+len) hits stale tail page returns old data Fix by reading pos back from iocb->ki_pos after generic_write_checks(), as generic_file_direct_write() does. Also fix a typo in the comment ("may have" -> "may have competed").
References
Impacted products
Vendor Product Version
Linux Linux Version: 2b0408d0284f4ff376cf5610fa8c9905e93c2541
Version: 2b0408d0284f4ff376cf5610fa8c9905e93c2541
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fuse/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "833963069adf86dcbdffd4e7d7b3171f95070b77",
              "status": "affected",
              "version": "2b0408d0284f4ff376cf5610fa8c9905e93c2541",
              "versionType": "git"
            },
            {
              "lessThan": "26d7e1f5c407b5859122b5cd47d7ebbf4b4c1cd2",
              "status": "affected",
              "version": "2b0408d0284f4ff376cf5610fa8c9905e93c2541",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/fuse/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: invalidate the correct range after O_APPEND direct write\n\nfuse_direct_write_iter() captures pos before generic_write_checks(),\nwhich moves ki_pos to EOF for O_APPEND writes:\n\n  fuse_direct_write_iter()\n  {\n      pos = iocb-\u003eki_pos;           /* 0 (user-supplied)       */\n      generic_write_checks();       /* ki_pos -\u003e EOF           */\n      fuse_direct_io();             /* writes at EOF, correct  */\n      invalidate(pos, pos + res);   /* [0, res) -- wrong       */\n  }\n\nThe post-write invalidation targets a stale range instead of the\nactual written range at EOF.\n\nThis can cause data inconsistency when the file size is not\npage-aligned.  The tail page straddling EOF has a valid portion\nbefore EOF that concurrent readers can fault back in during the\nDIO write window:\n\n  Tail page (file size X not page-aligned):\n\n    page_start         X (EOF)   page_end\n    |--- valid data ----|-- stale --|\n\n  CPU0 (O_APPEND DIO writer)    CPU1 (buffered reader)\n  --------------------------    ----------------------\n  invalidate [X, X+len)\n    tail page evicted\n  FUSE_WRITE in flight ...\n                                read [page_start, X)\n                                  tail page re-faulted\n                                  [X, page_end) = stale\n  FUSE_WRITE completes\n  i_size = X + len\n  invalidate [0, len)  \u003c- WRONG\n    tail page still cached\n                                read [X, X+len)\n                                  hits stale tail page\n                                  returns old data\n\nFix by reading pos back from iocb-\u003eki_pos after generic_write_checks(),\nas generic_file_direct_write() does.\n\nAlso fix a typo in the comment (\"may have\" -\u003e \"may have competed\")."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:54.506Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/833963069adf86dcbdffd4e7d7b3171f95070b77"
        },
        {
          "url": "https://git.kernel.org/stable/c/26d7e1f5c407b5859122b5cd47d7ebbf4b4c1cd2"
        }
      ],
      "title": "fuse: invalidate the correct range after O_APPEND direct write",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90096",
    "datePublished": "2026-09-17T16:06:08.870Z",
    "dateReserved": "2026-09-11T19:38:34.786Z",
    "dateUpdated": "2026-10-19T08:57:54.506Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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