CVE-2026-92500 (GCVE-0-2026-92500)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:10 – Updated: 2026-10-19 09:04
VLAI
Title
ext4: use fsdata to track inline data write state and fix race
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: use fsdata to track inline data write state and fix race Instead of checking the live inode state (ext4_has_inline_data(inode) and ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) in the write_end handlers, use the fsdata parameter of the address space operations to explicitly pass down the state in which write_begin prepared the write. A concurrent thread (such as ext4_page_mkwrite()) can convert the inline data to an extent between write_begin and write_end. If this happens, the write_end handlers would previously miss the inline write_end path and fall through to extent-based write_end logic. However, since block buffers were never allocated in write_begin, this resulted in NULL pointer dereferences or data loss because folio_buffers(folio) was NULL. Define EXT4_WRITE_DATA_INLINE (4) as a bit flag (Bit 2), treating fsdata as bitwise flags rather than mutually exclusive enums to keep states of the write path independent. Communicate this state via fsdata: 1) ext4_write_begin() and ext4_da_write_begin() set the EXT4_WRITE_DATA_INLINE bit in *fsdata via bitwise OR when an inline write is successfully prepared. 2) On entry, ext4_write_begin() clears the EXT4_WRITE_DATA_INLINE bit to safely handle VFS retries (where generic_perform_write() bypasses the fsdata initialization on its retry jump). 3) The write_end handlers perform a bitwise AND to check if the EXT4_WRITE_DATA_INLINE bit is set and invoke the inline write_end helper accordingly. Furthermore, during a buffered write, ext4_write_inline_data_end() acquires the xattr lock after preparing the write. If a concurrent page fault (ext4_page_mkwrite()) converts the inline data to an extent after the write_end handlers check the state but before ext4_write_inline_data_end() acquires the xattr write lock, the subsequent check will trigger a kernel panic via BUG_ON(!ext4_has_inline_data(inode)). To keep git history working and bisectability clean, replace the BUG_ON check in ext4_write_inline_data_end() with a graceful error- handling retry path in this same commit. If the inline data is cleared after locking the xattr, we safely release all resources (releasing iloc.bh, unlocking/putting the folio, stopping the active journal transaction handle) and return 0 (VFS retry) to let the generic write path retry the operation safely.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7067 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3fdcfb668fd78ec92d9bc2daddf1d41e2a8a30bb , < bd8d74bd46d09905164255b8635fa58b45f41068 (git)
Affected: 3fdcfb668fd78ec92d9bc2daddf1d41e2a8a30bb , < 439aedfd7ae868d1d7b4930afe66091cb979cd5c (git)
Affected: 3fdcfb668fd78ec92d9bc2daddf1d41e2a8a30bb , < 7edbb323bab2b2a609016014caafdb651c898249 (git)
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Linux Linux Affected: 3.8
Unaffected: 0 , < 3.8 (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ext4/ext4.h",
            "fs/ext4/inline.c",
            "fs/ext4/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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            "fs/ext4/inline.c",
            "fs/ext4/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.8"
            },
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              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
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      ],
      "cpeApplicability": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
                  "versionStartIncluding": "3.8",
                  "vulnerable": true
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                  "versionEndExcluding": "7.2.6",
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                },
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
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                  "vulnerable": true
                }
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: use fsdata to track inline data write state and fix race\n\nInstead of checking the live inode state (ext4_has_inline_data(inode)\nand ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) in the\nwrite_end handlers, use the fsdata parameter of the address space\noperations to explicitly pass down the state in which write_begin\nprepared the write.\n\nA concurrent thread (such as ext4_page_mkwrite()) can convert the\ninline data to an extent between write_begin and write_end. If this\nhappens, the write_end handlers would previously miss the inline\nwrite_end path and fall through to extent-based write_end logic.\nHowever, since block buffers were never allocated in write_begin,\nthis resulted in NULL pointer dereferences or data loss because\nfolio_buffers(folio) was NULL.\n\nDefine EXT4_WRITE_DATA_INLINE (4) as a bit flag (Bit 2), treating\nfsdata as bitwise flags rather than mutually exclusive enums to keep\nstates of the write path independent. Communicate this state via\nfsdata:\n1) ext4_write_begin() and ext4_da_write_begin() set the\n   EXT4_WRITE_DATA_INLINE bit in *fsdata via bitwise OR when an inline\n   write is successfully prepared.\n2) On entry, ext4_write_begin() clears the EXT4_WRITE_DATA_INLINE bit\n   to safely handle VFS retries (where generic_perform_write() bypasses\n   the fsdata initialization on its retry jump).\n3) The write_end handlers perform a bitwise AND to check if the\n   EXT4_WRITE_DATA_INLINE bit is set and invoke the inline write_end\n   helper accordingly.\n\nFurthermore, during a buffered write, ext4_write_inline_data_end()\nacquires the xattr lock after preparing the write. If a concurrent\npage fault (ext4_page_mkwrite()) converts the inline data to an extent\nafter the write_end handlers check the state but before\next4_write_inline_data_end() acquires the xattr write lock, the\nsubsequent check will trigger a kernel panic via\nBUG_ON(!ext4_has_inline_data(inode)).\n\nTo keep git history working and bisectability clean, replace the\nBUG_ON check in ext4_write_inline_data_end() with a graceful error-\nhandling retry path in this same commit. If the inline data is cleared\nafter locking the xattr, we safely release all resources (releasing\niloc.bh, unlocking/putting the folio, stopping the active journal\ntransaction handle) and return 0 (VFS retry) to let the generic write\npath retry the operation safely."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:04:06.284Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bd8d74bd46d09905164255b8635fa58b45f41068"
        },
        {
          "url": "https://git.kernel.org/stable/c/439aedfd7ae868d1d7b4930afe66091cb979cd5c"
        },
        {
          "url": "https://git.kernel.org/stable/c/7edbb323bab2b2a609016014caafdb651c898249"
        }
      ],
      "title": "ext4: use fsdata to track inline data write state and fix race",
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      }
    }
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-92500",
    "datePublished": "2026-09-17T16:10:14.073Z",
    "dateReserved": "2026-09-16T12:21:13.871Z",
    "dateUpdated": "2026-10-19T09:04:06.284Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-92500",
      "date": "2026-10-26",
      "epss": "0.00219",
      "percentile": "0.12298"
    },
    "nvd": {
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                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
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                  "fs/ext4/inline.c",
                  "fs/ext4/inode.c"
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                ],
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                "vendor": "Linux",
                "versions": [
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                    "version": "6.18.52",
                    "versionType": "semver"
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                    "status": "unaffected",
                    "version": "7.2.6",
                    "versionType": "semver"
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                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: use fsdata to track inline data write state and fix race\n\nInstead of checking the live inode state (ext4_has_inline_data(inode)\nand ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) in the\nwrite_end handlers, use the fsdata parameter of the address space\noperations to explicitly pass down the state in which write_begin\nprepared the write.\n\nA concurrent thread (such as ext4_page_mkwrite()) can convert the\ninline data to an extent between write_begin and write_end. If this\nhappens, the write_end handlers would previously miss the inline\nwrite_end path and fall through to extent-based write_end logic.\nHowever, since block buffers were never allocated in write_begin,\nthis resulted in NULL pointer dereferences or data loss because\nfolio_buffers(folio) was NULL.\n\nDefine EXT4_WRITE_DATA_INLINE (4) as a bit flag (Bit 2), treating\nfsdata as bitwise flags rather than mutually exclusive enums to keep\nstates of the write path independent. Communicate this state via\nfsdata:\n1) ext4_write_begin() and ext4_da_write_begin() set the\n   EXT4_WRITE_DATA_INLINE bit in *fsdata via bitwise OR when an inline\n   write is successfully prepared.\n2) On entry, ext4_write_begin() clears the EXT4_WRITE_DATA_INLINE bit\n   to safely handle VFS retries (where generic_perform_write() bypasses\n   the fsdata initialization on its retry jump).\n3) The write_end handlers perform a bitwise AND to check if the\n   EXT4_WRITE_DATA_INLINE bit is set and invoke the inline write_end\n   helper accordingly.\n\nFurthermore, during a buffered write, ext4_write_inline_data_end()\nacquires the xattr lock after preparing the write. If a concurrent\npage fault (ext4_page_mkwrite()) converts the inline data to an extent\nafter the write_end handlers check the state but before\next4_write_inline_data_end() acquires the xattr write lock, the\nsubsequent check will trigger a kernel panic via\nBUG_ON(!ext4_has_inline_data(inode)).\n\nTo keep git history working and bisectability clean, replace the\nBUG_ON check in ext4_write_inline_data_end() with a graceful error-\nhandling retry path in this same commit. If the inline data is cleared\nafter locking the xattr, we safely release all resources (releasing\niloc.bh, unlocking/putting the folio, stopping the active journal\ntransaction handle) and return 0 (VFS retry) to let the generic write\npath retry the operation safely."
          }
        ],
        "id": "CVE-2026-92500",
        "lastModified": "2026-10-19T09:19:40.247",
        "metrics": {},
        "published": "2026-09-17T17:17:52.400",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          {
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-23T00:15:54+00:00",
      "cve": "CVE-2026-92500",
      "id": "CVE-2026-92500",
      "initial_release_date": "2026-09-17T00:00:00+00:00",
      "product_status:known_affected": "278",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ext4: use fsdata to track inline data write state and fix race",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92500.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-20T00:31:44Z",
      "cve": "CVE-2026-92500",
      "id": "CVE-2026-92500",
      "initial_release_date": "2026-09-18T00:13:39Z",
      "product_status:known_affected": "712",
      "product_status:known_not_affected": "4",
      "product_status:recommended": "100",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-92500",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-92500.json",
      "version": "8"
    }
  }
}



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