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GHSA-5PG7-FR46-JX8J

Vulnerability from github – Published: 2026-05-01 15:30 – Updated: 2026-05-06 21:31

Details

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

f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io()

The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference.

The concurrent scenario that triggers the panic is as follows:

F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic

The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic.

This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition.

Severity ?

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-31715"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-01T14:16:21Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix UAF caused by decrementing sbi-\u003enr_pages[] in f2fs_write_end_io()\n\nThe xfstests case \"generic/107\" and syzbot have both reported a NULL\npointer dereference.\n\nThe concurrent scenario that triggers the panic is as follows:\n\nF2FS_WB_CP_DATA write callback          umount\n                                        - f2fs_write_checkpoint\n                                         - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA)\n- blk_mq_end_request\n - bio_endio\n  - f2fs_write_end_io\n   : dec_page_count(sbi, F2FS_WB_CP_DATA)\n   : wake_up(\u0026sbi-\u003ecp_wait)\n                                        - kill_f2fs_super\n                                         - kill_block_super\n                                          - f2fs_put_super\n                                           : iput(sbi-\u003enode_inode)\n                                           : sbi-\u003enode_inode = NULL\n   : f2fs_in_warm_node_list\n    - is_node_folio // sbi-\u003enode_inode is NULL and panic\n\nThe root cause is that f2fs_put_super() calls iput(sbi-\u003enode_inode) and\nsets sbi-\u003enode_inode to NULL after sbi-\u003enr_pages[F2FS_WB_CP_DATA] is\ndecremented to zero. As a result, f2fs_in_warm_node_list() may\ndereference a NULL node_inode when checking whether a folio belongs to\nthe node inode, leading to a panic.\n\nThis patch fixes the issue by calling f2fs_in_warm_node_list() before\ndecrementing sbi-\u003enr_pages[F2FS_WB_CP_DATA], thus preventing the\nuse-after-free condition.",
  "id": "GHSA-5pg7-fr46-jx8j",
  "modified": "2026-05-06T21:31:32Z",
  "published": "2026-05-01T15:30:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31715"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/188bb65f247a7a7c62f287c9a263aee3cad96fa5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/963d2e24d9d92a31e6773b0f642214f10013ebf7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-31715 (GCVE-0-2026-31715)

Vulnerability from cvelistv5 – Published: 2026-05-01 13:56 – Updated: 2026-05-01 13:56

Title

f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io()

Summary

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io() The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference. The concurrent scenario that triggers the panic is as follows: F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic. This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition.

Severity ?

No CVSS data available.

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/963d2e24d9d92a31e…
	https://git.kernel.org/stable/c/188bb65f247a7a7c6…
	https://git.kernel.org/stable/c/2d9c4a4ed4eef1f82…

Impacted products

Vendor

Product

Version

Linux

Affected: 50fa53eccf9f911a5b435248a2b0bd484fd82e5e , < 963d2e24d9d92a31e6773b0f642214f10013ebf7 (git)
Affected: 50fa53eccf9f911a5b435248a2b0bd484fd82e5e , < 188bb65f247a7a7c62f287c9a263aee3cad96fa5 (git)
Affected: 50fa53eccf9f911a5b435248a2b0bd484fd82e5e , < 2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 (git)

Linux

Affected: 4.19
Unaffected: 0 , < 4.19 (semver)
Unaffected: 6.18.25 , ≤ 6.18.* (semver)
Unaffected: 7.0.2 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/data.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "963d2e24d9d92a31e6773b0f642214f10013ebf7",
              "status": "affected",
              "version": "50fa53eccf9f911a5b435248a2b0bd484fd82e5e",
              "versionType": "git"
            },
            {
              "lessThan": "188bb65f247a7a7c62f287c9a263aee3cad96fa5",
              "status": "affected",
              "version": "50fa53eccf9f911a5b435248a2b0bd484fd82e5e",
              "versionType": "git"
            },
            {
              "lessThan": "2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53",
              "status": "affected",
              "version": "50fa53eccf9f911a5b435248a2b0bd484fd82e5e",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/data.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.19"
            },
            {
              "lessThan": "4.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.25",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.25",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.2",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1-rc1",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix UAF caused by decrementing sbi-\u003enr_pages[] in f2fs_write_end_io()\n\nThe xfstests case \"generic/107\" and syzbot have both reported a NULL\npointer dereference.\n\nThe concurrent scenario that triggers the panic is as follows:\n\nF2FS_WB_CP_DATA write callback          umount\n                                        - f2fs_write_checkpoint\n                                         - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA)\n- blk_mq_end_request\n - bio_endio\n  - f2fs_write_end_io\n   : dec_page_count(sbi, F2FS_WB_CP_DATA)\n   : wake_up(\u0026sbi-\u003ecp_wait)\n                                        - kill_f2fs_super\n                                         - kill_block_super\n                                          - f2fs_put_super\n                                           : iput(sbi-\u003enode_inode)\n                                           : sbi-\u003enode_inode = NULL\n   : f2fs_in_warm_node_list\n    - is_node_folio // sbi-\u003enode_inode is NULL and panic\n\nThe root cause is that f2fs_put_super() calls iput(sbi-\u003enode_inode) and\nsets sbi-\u003enode_inode to NULL after sbi-\u003enr_pages[F2FS_WB_CP_DATA] is\ndecremented to zero. As a result, f2fs_in_warm_node_list() may\ndereference a NULL node_inode when checking whether a folio belongs to\nthe node inode, leading to a panic.\n\nThis patch fixes the issue by calling f2fs_in_warm_node_list() before\ndecrementing sbi-\u003enr_pages[F2FS_WB_CP_DATA], thus preventing the\nuse-after-free condition."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-01T13:56:10.591Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/963d2e24d9d92a31e6773b0f642214f10013ebf7"
        },
        {
          "url": "https://git.kernel.org/stable/c/188bb65f247a7a7c62f287c9a263aee3cad96fa5"
        },
        {
          "url": "https://git.kernel.org/stable/c/2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53"
        }
      ],
      "title": "f2fs: fix UAF caused by decrementing sbi-\u003enr_pages[] in f2fs_write_end_io()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31715",
    "datePublished": "2026-05-01T13:56:10.591Z",
    "dateReserved": "2026-03-09T15:48:24.133Z",
    "dateUpdated": "2026-05-01T13:56:10.591Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-5PG7-FR46-JX8J

CVE-2026-31715 (GCVE-0-2026-31715)

Tags

Sightings

Nomenclature