Vulnerability-Lookup

GHSA-8VW8-R4JR-VP93

Vulnerability from github – Published: 2026-04-22 15:31 – Updated: 2026-04-22 15:31

Details

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

ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()

smb_grant_oplock() has two issues in the oplock publication sequence:

1) opinfo is linked into ci->m_op_list (via opinfo_add) before add_lease_global_list() is called. If add_lease_global_list() fails (kmalloc returns NULL), the error path frees the opinfo via __free_opinfo() while it is still linked in ci->m_op_list. Concurrent m_op_list readers (opinfo_get_list, or direct iteration in smb_break_all_levII_oplock) dereference the freed node.

2) opinfo->o_fp is assigned after add_lease_global_list() publishes the opinfo on the global lease list. A concurrent find_same_lease_key() can walk the lease list and dereference opinfo->o_fp->f_ci while o_fp is still NULL.

Fix by restructuring the publication sequence to eliminate post-publish failure:

Set opinfo->o_fp before any list publication (fixes NULL deref).
Preallocate lease_table via alloc_lease_table() before opinfo_add() so add_lease_global_list() becomes infallible after publication.
Keep the original m_op_list publication order (opinfo_add before lease list) so concurrent opens via same_client_has_lease() and opinfo_get_list() still see the in-flight grant.
Use opinfo_put() instead of __free_opinfo() on err_out so that the RCU-deferred free path is used.

This also requires splitting add_lease_global_list() to take a preallocated lease_table and changing its return type from int to void, since it can no longer fail.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-31444"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-22T14:16:38Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free and NULL deref in smb_grant_oplock()\n\nsmb_grant_oplock() has two issues in the oplock publication sequence:\n\n1) opinfo is linked into ci-\u003em_op_list (via opinfo_add) before\n   add_lease_global_list() is called.  If add_lease_global_list()\n   fails (kmalloc returns NULL), the error path frees the opinfo\n   via __free_opinfo() while it is still linked in ci-\u003em_op_list.\n   Concurrent m_op_list readers (opinfo_get_list, or direct iteration\n   in smb_break_all_levII_oplock) dereference the freed node.\n\n2) opinfo-\u003eo_fp is assigned after add_lease_global_list() publishes\n   the opinfo on the global lease list.  A concurrent\n   find_same_lease_key() can walk the lease list and dereference\n   opinfo-\u003eo_fp-\u003ef_ci while o_fp is still NULL.\n\nFix by restructuring the publication sequence to eliminate post-publish\nfailure:\n\n- Set opinfo-\u003eo_fp before any list publication (fixes NULL deref).\n- Preallocate lease_table via alloc_lease_table() before opinfo_add()\n  so add_lease_global_list() becomes infallible after publication.\n- Keep the original m_op_list publication order (opinfo_add before\n  lease list) so concurrent opens via same_client_has_lease() and\n  opinfo_get_list() still see the in-flight grant.\n- Use opinfo_put() instead of __free_opinfo() on err_out so that\n  the RCU-deferred free path is used.\n\nThis also requires splitting add_lease_global_list() to take a\npreallocated lease_table and changing its return type from int to void,\nsince it can no longer fail.",
  "id": "GHSA-8vw8-r4jr-vp93",
  "modified": "2026-04-22T15:31:40Z",
  "published": "2026-04-22T15:31:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31444"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/48623ec358c1c600fa1e38368746f933e0f1a617"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6d7e5a918c1d0aad06db0e17677b66fc9a471021"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7de55bba69cbf0f9280daaea385daf08bc076121"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e785f004cbc56390479b77375726ea9b0d1a8a6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a5c6f6d6ceefed2d5210ee420fb75f8362461f46"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-31444 (GCVE-0-2026-31444)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:53 – Updated: 2026-04-22 13:53

Title

ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free and NULL deref in smb_grant_oplock() smb_grant_oplock() has two issues in the oplock publication sequence: 1) opinfo is linked into ci->m_op_list (via opinfo_add) before add_lease_global_list() is called. If add_lease_global_list() fails (kmalloc returns NULL), the error path frees the opinfo via __free_opinfo() while it is still linked in ci->m_op_list. Concurrent m_op_list readers (opinfo_get_list, or direct iteration in smb_break_all_levII_oplock) dereference the freed node. 2) opinfo->o_fp is assigned after add_lease_global_list() publishes the opinfo on the global lease list. A concurrent find_same_lease_key() can walk the lease list and dereference opinfo->o_fp->f_ci while o_fp is still NULL. Fix by restructuring the publication sequence to eliminate post-publish failure: - Set opinfo->o_fp before any list publication (fixes NULL deref). - Preallocate lease_table via alloc_lease_table() before opinfo_add() so add_lease_global_list() becomes infallible after publication. - Keep the original m_op_list publication order (opinfo_add before lease list) so concurrent opens via same_client_has_lease() and opinfo_get_list() still see the in-flight grant. - Use opinfo_put() instead of __free_opinfo() on err_out so that the RCU-deferred free path is used. This also requires splitting add_lease_global_list() to take a preallocated lease_table and changing its return type from int to void, since it can no longer fail.

Severity ?

No CVSS data available.

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/9e785f004cbc56390…
	https://git.kernel.org/stable/c/7de55bba69cbf0f92…
	https://git.kernel.org/stable/c/a5c6f6d6ceefed2d5…
	https://git.kernel.org/stable/c/6d7e5a918c1d0aad0…
	https://git.kernel.org/stable/c/48623ec358c1c600f…

Impacted products

Vendor

Product

Version

Linux

Affected: 302fef75512b2c8329a3f5efab1ae7ba2562387a , < 9e785f004cbc56390479b77375726ea9b0d1a8a6 (git)
Affected: 08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c , < 7de55bba69cbf0f9280daaea385daf08bc076121 (git)
Affected: 1d6abf145615dbfe267ce3b0a271f95e3780e18e , < a5c6f6d6ceefed2d5210ee420fb75f8362461f46 (git)
Affected: ce8507ee82c888126d8e7565e27c016308d24cde , < 6d7e5a918c1d0aad06db0e17677b66fc9a471021 (git)
Affected: 1dfd062caa165ec9d7ee0823087930f3ab8a6294 , < 48623ec358c1c600fa1e38368746f933e0f1a617 (git)

Linux

Affected: 6.6.130 , < 6.6.131 (semver)
Affected: 6.12.78 , < 6.12.80 (semver)
Affected: 6.18.19 , < 6.18.21 (semver)
Affected: 6.19.9 , < 6.19.11 (semver)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/oplock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9e785f004cbc56390479b77375726ea9b0d1a8a6",
              "status": "affected",
              "version": "302fef75512b2c8329a3f5efab1ae7ba2562387a",
              "versionType": "git"
            },
            {
              "lessThan": "7de55bba69cbf0f9280daaea385daf08bc076121",
              "status": "affected",
              "version": "08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c",
              "versionType": "git"
            },
            {
              "lessThan": "a5c6f6d6ceefed2d5210ee420fb75f8362461f46",
              "status": "affected",
              "version": "1d6abf145615dbfe267ce3b0a271f95e3780e18e",
              "versionType": "git"
            },
            {
              "lessThan": "6d7e5a918c1d0aad06db0e17677b66fc9a471021",
              "status": "affected",
              "version": "ce8507ee82c888126d8e7565e27c016308d24cde",
              "versionType": "git"
            },
            {
              "lessThan": "48623ec358c1c600fa1e38368746f933e0f1a617",
              "status": "affected",
              "version": "1dfd062caa165ec9d7ee0823087930f3ab8a6294",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/oplock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6.6.131",
              "status": "affected",
              "version": "6.6.130",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.80",
              "status": "affected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18.21",
              "status": "affected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThan": "6.19.11",
              "status": "affected",
              "version": "6.19.9",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.131",
                  "versionStartIncluding": "6.6.130",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.80",
                  "versionStartIncluding": "6.12.78",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.21",
                  "versionStartIncluding": "6.18.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "versionStartIncluding": "6.19.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free and NULL deref in smb_grant_oplock()\n\nsmb_grant_oplock() has two issues in the oplock publication sequence:\n\n1) opinfo is linked into ci-\u003em_op_list (via opinfo_add) before\n   add_lease_global_list() is called.  If add_lease_global_list()\n   fails (kmalloc returns NULL), the error path frees the opinfo\n   via __free_opinfo() while it is still linked in ci-\u003em_op_list.\n   Concurrent m_op_list readers (opinfo_get_list, or direct iteration\n   in smb_break_all_levII_oplock) dereference the freed node.\n\n2) opinfo-\u003eo_fp is assigned after add_lease_global_list() publishes\n   the opinfo on the global lease list.  A concurrent\n   find_same_lease_key() can walk the lease list and dereference\n   opinfo-\u003eo_fp-\u003ef_ci while o_fp is still NULL.\n\nFix by restructuring the publication sequence to eliminate post-publish\nfailure:\n\n- Set opinfo-\u003eo_fp before any list publication (fixes NULL deref).\n- Preallocate lease_table via alloc_lease_table() before opinfo_add()\n  so add_lease_global_list() becomes infallible after publication.\n- Keep the original m_op_list publication order (opinfo_add before\n  lease list) so concurrent opens via same_client_has_lease() and\n  opinfo_get_list() still see the in-flight grant.\n- Use opinfo_put() instead of __free_opinfo() on err_out so that\n  the RCU-deferred free path is used.\n\nThis also requires splitting add_lease_global_list() to take a\npreallocated lease_table and changing its return type from int to void,\nsince it can no longer fail."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-22T13:53:41.351Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9e785f004cbc56390479b77375726ea9b0d1a8a6"
        },
        {
          "url": "https://git.kernel.org/stable/c/7de55bba69cbf0f9280daaea385daf08bc076121"
        },
        {
          "url": "https://git.kernel.org/stable/c/a5c6f6d6ceefed2d5210ee420fb75f8362461f46"
        },
        {
          "url": "https://git.kernel.org/stable/c/6d7e5a918c1d0aad06db0e17677b66fc9a471021"
        },
        {
          "url": "https://git.kernel.org/stable/c/48623ec358c1c600fa1e38368746f933e0f1a617"
        }
      ],
      "title": "ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31444",
    "datePublished": "2026-04-22T13:53:41.351Z",
    "dateReserved": "2026-03-09T15:48:24.090Z",
    "dateUpdated": "2026-04-22T13:53:41.351Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

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-8VW8-R4JR-VP93

CVE-2026-31444 (GCVE-0-2026-31444)

Tags

Sightings

Nomenclature