GHSA-F6CQ-3VQ2-5393

Vulnerability from github – Published: 2024-11-07 12:30 – Updated: 2025-11-04 00:31
VLAI
Details

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

bpf: Make sure internal and UAPI bpf_redirect flags don't overlap

The bpf_redirect_info is shared between the SKB and XDP redirect paths, and the two paths use the same numeric flag values in the ri->flags field (specifically, BPF_F_BROADCAST == BPF_F_NEXTHOP). This means that if skb bpf_redirect_neigh() is used with a non-NULL params argument and, subsequently, an XDP redirect is performed using the same bpf_redirect_info struct, the XDP path will get confused and end up crashing, which syzbot managed to trigger.

With the stack-allocated bpf_redirect_info, the structure is no longer shared between the SKB and XDP paths, so the crash doesn't happen anymore. However, different code paths using identically-numbered flag values in the same struct field still seems like a bit of a mess, so this patch cleans that up by moving the flag definitions together and redefining the three flags in BPF_F_REDIRECT_INTERNAL to not overlap with the flags used for XDP. It also adds a BUILD_BUG_ON() check to make sure the overlap is not re-introduced by mistake.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-50163"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-11-07T10:15:07Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Make sure internal and UAPI bpf_redirect flags don\u0027t overlap\n\nThe bpf_redirect_info is shared between the SKB and XDP redirect paths,\nand the two paths use the same numeric flag values in the ri-\u003eflags\nfield (specifically, BPF_F_BROADCAST == BPF_F_NEXTHOP). This means that\nif skb bpf_redirect_neigh() is used with a non-NULL params argument and,\nsubsequently, an XDP redirect is performed using the same\nbpf_redirect_info struct, the XDP path will get confused and end up\ncrashing, which syzbot managed to trigger.\n\nWith the stack-allocated bpf_redirect_info, the structure is no longer\nshared between the SKB and XDP paths, so the crash doesn\u0027t happen\nanymore. However, different code paths using identically-numbered flag\nvalues in the same struct field still seems like a bit of a mess, so\nthis patch cleans that up by moving the flag definitions together and\nredefining the three flags in BPF_F_REDIRECT_INTERNAL to not overlap\nwith the flags used for XDP. It also adds a BUILD_BUG_ON() check to make\nsure the overlap is not re-introduced by mistake.",
  "id": "GHSA-f6cq-3vq2-5393",
  "modified": "2025-11-04T00:31:57Z",
  "published": "2024-11-07T12:30:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-50163"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09d88791c7cd888d5195c84733caf9183dcfbd16"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0fca5ed4be8e8bfbfb9bd97845af596bab7192d3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/314dbee9fe4f5cee36435465de52c988d7caa466"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4e1e428533845d48828bd3875c0e92e8565b9962"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cec288e05ceac9a0d3a3a1fd279534b11844c826"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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