GHSA-3V8X-C22J-HV4Q

Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-05-11 09:30
VLAI
Details

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

ksmbd: fix use-after-free by using call_rcu() for oplock_info

ksmbd currently frees oplock_info immediately using kfree(), even though it is accessed under RCU read-side critical sections in places like opinfo_get() and proc_show_files().

Since there is no RCU grace period delay between nullifying the pointer and freeing the memory, a reader can still access oplock_info structure after it has been freed. This can leads to a use-after-free especially in opinfo_get() where atomic_inc_not_zero() is called on already freed memory.

Fix this by switching to deferred freeing using call_rcu().

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-43376"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-08T15:16:48Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free by using call_rcu() for oplock_info\n\nksmbd currently frees oplock_info immediately using kfree(), even\nthough it is accessed under RCU read-side critical sections in places\nlike opinfo_get() and proc_show_files().\n\nSince there is no RCU grace period delay between nullifying the pointer\nand freeing the memory, a reader can still access oplock_info\nstructure after it has been freed. This can leads to a use-after-free\nespecially in opinfo_get() where atomic_inc_not_zero() is called on\nalready freed memory.\n\nFix this by switching to deferred freeing using call_rcu().",
  "id": "GHSA-3v8x-c22j-hv4q",
  "modified": "2026-05-11T09:30:30Z",
  "published": "2026-05-08T15:31:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43376"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1d6abf145615dbfe267ce3b0a271f95e3780e18e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1dfd062caa165ec9d7ee0823087930f3ab8a6294"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/302fef75512b2c8329a3f5efab1ae7ba2562387a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ce8507ee82c888126d8e7565e27c016308d24cde"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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