GHSA-J9M2-MP7M-3W46

Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-18 18:31
VLAI
Details

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

bpf: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux

bpf_get_btf_vmlinux() lazily parses the vmlinux BTF under the bpf_verifier_lock, but publishes the result through a plain store and re-checks it through a plain lockless load. Nothing orders the stores initializing the struct btf inside btf_parse_vmlinux() against the store publishing the pointer: On a weakly ordered arch, a concurrent first-time caller taking the lockless fast path could in principle observe the pointer before the parsed contents are visible. The mutex_unlock() does not help such a reader given it only synchronizes with a later acquisition of the same lock. Thus, publish the pointer with smp_store_release() and read it on the fast path with smp_load_acquire().

Acquire semantics are needed rather than a dependency-ordered READ_ONCE(): btf_parse_vmlinux() also populates globals outside the returned object (e.g. bpf_ctx_convert.t). An address dependency would only order accesses performed through the pointer and not cover other globals.

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-2026-93138"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:18:08Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux\n\nbpf_get_btf_vmlinux() lazily parses the vmlinux BTF under the\nbpf_verifier_lock, but publishes the result through a plain store\nand re-checks it through a plain lockless load. Nothing orders\nthe stores initializing the struct btf inside btf_parse_vmlinux()\nagainst the store publishing the pointer: On a weakly ordered\narch, a concurrent first-time caller taking the lockless fast\npath could in principle observe the pointer before the parsed\ncontents are visible. The mutex_unlock() does not help such a\nreader given it only synchronizes with a later acquisition of the\nsame lock. Thus, publish the pointer with smp_store_release()\nand read it on the fast path with smp_load_acquire().\n\nAcquire semantics are needed rather than a dependency-ordered\nREAD_ONCE(): btf_parse_vmlinux() also populates globals outside\nthe returned object (e.g. bpf_ctx_convert.t). An address\ndependency would only order accesses performed through the\npointer and not cover other globals.",
  "id": "GHSA-j9m2-mp7m-3w46",
  "modified": "2026-09-18T18:31:34Z",
  "published": "2026-09-17T18:32:11Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93138"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2892f3f44bf865c8fb6b6c0960edec4cc91806ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/86d11c594d60b255b526fa5260f669463fb1a063"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/92863e678070f57c17c868e4bfa2441a5c61ad2b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/978524ecfc1c539282df5858de1eec20748c6f74"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a7fe72d780122eb934536f1719abad445f6afdf7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e18a10b39c994f04e1ebd7f8fc042bb1ca8ad053"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eaf302628a78806f66d8224d6ba03fb4d5025de4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f32a4a40bc635be25d6816da4bd91e9e58c31bf3"
    }
  ],
  "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"
    }
  ]
}



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