ghsa-rvq5-xw4g-6wj7
Vulnerability from github
Published
2025-10-28 12:30
Modified
2025-10-29 15:31
Details

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

bpf: Explicitly check accesses to bpf_sock_addr

Syzkaller found a kernel warning on the following sock_addr program:

0: r0 = 0
1: r2 = *(u32 *)(r1 +60)
2: exit

which triggers:

verifier bug: error during ctx access conversion (0)

This is happening because offset 60 in bpf_sock_addr corresponds to an implicit padding of 4 bytes, right after msg_src_ip4. Access to this padding isn't rejected in sock_addr_is_valid_access and it thus later fails to convert the access.

This patch fixes it by explicitly checking the various fields of bpf_sock_addr in sock_addr_is_valid_access.

I checked the other ctx structures and is_valid_access functions and didn't find any other similar cases. Other cases of (properly handled) padding are covered in new tests in a subsequent patch.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-40078"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-10-28T12:15:42Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Explicitly check accesses to bpf_sock_addr\n\nSyzkaller found a kernel warning on the following sock_addr program:\n\n    0: r0 = 0\n    1: r2 = *(u32 *)(r1 +60)\n    2: exit\n\nwhich triggers:\n\n    verifier bug: error during ctx access conversion (0)\n\nThis is happening because offset 60 in bpf_sock_addr corresponds to an\nimplicit padding of 4 bytes, right after msg_src_ip4. Access to this\npadding isn\u0027t rejected in sock_addr_is_valid_access and it thus later\nfails to convert the access.\n\nThis patch fixes it by explicitly checking the various fields of\nbpf_sock_addr in sock_addr_is_valid_access.\n\nI checked the other ctx structures and is_valid_access functions and\ndidn\u0027t find any other similar cases. Other cases of (properly handled)\npadding are covered in new tests in a subsequent patch.",
  "id": "GHSA-rvq5-xw4g-6wj7",
  "modified": "2025-10-29T15:31:53Z",
  "published": "2025-10-28T12:30:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40078"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4f00858cd9bbbdf67159e28b85a8ca9e77c83622"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6d8b1a21fd5c34622b0c3893c61e4a38d8ba53ec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6fabca2fc94d33cdf7ec102058983b086293395f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/76e04bbb4296fb6eac084dbfc27e02ccc744db3e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ad8b4fe5617e3c85fc23267f02500c4f3bf0ff69"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cdeafacb4f9ff261a96baef519e29480fd7b1019"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de44cdc50d2dce8718cb57deddf9cf1be9a7759f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fe9d33f0470350558cb08cecb54cf2267b3a45d2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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