fou: Fix null-ptr-deref in GRO.

{
  "id": "fc364cf067cb47d49c593df73ac4b886b1e4a4a61c5d24c00f897874c12029f2",
  "url": "https://osv.dev/vulnerability/CVE-2024-46763",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fou: Fix null-ptr-deref in GRO.",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: fou: Fix null-ptr-deref in GRO. We observed a null-ptr-deref in fou_gro_receive() while shutting down a host. [0] The NULL pointer is sk->sk_user_data, and the offset 8 is of protocol in struct fou. When fou_release() is called due to netns dismantle or explicit tunnel teardown, udp_tunnel_sock_release() sets NULL to sk->sk_user_data. Then, the tunnel socket is destroyed after a single RCU grace period. So, in-flight udp4_gro_receive() could find the socket and execute the FOU GRO handler, where sk->sk_user_data could be NULL. Let's use rcu_dereference_sk_user_data() in fou_from_sock() and add NULL checks in FOU GRO handlers. [0]: BUG: kernel NULL pointer dereference, address: 0000000000000008 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 80000001032f4067 P4D 80000001032f4067 PUD 103240067 PMD 0 SMP PTI CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.10.216-204.855.amzn2.x86_64 #1 Hardware name: Amazon EC2 c5.large/, BIOS 1.0 10/16/2017 RIP: 0010:fou_gro_receive (net/ipv4/fou.c:233) [fou] Code: 41 5f c3 cc cc cc cc e8 e7 2e 69 f4 0f 1f 80 00 00 00 00 0f 1f 44 00 00 49 89 f8 41 54 48 89 f7 48 89 d6 49 8b 80 88 02 00 00 <0f> b6 48 08 0f b7 42 4a 66 25 fd fd 80 cc 02 66 89 42 4a 0f b6 42 RSP: 0018:ffffa330c0003d08 EFLAGS: 00010297 RAX: 0000000000000000 RBX: ffff93d9e3a6b900 RCX: 0000000000000010 RDX: ffff93d9e3a6b900 RSI: ffff93d9e3a6b900 RDI: ffff93dac2e24d08 RBP: ffff93d9e",
    "evidence": "osv:CVE-2024-46763",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.226",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.167",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.110",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.51",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.10.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2024-46763",
      "aliases": [
        "CVE-2024-46763"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
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      "affected": [
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                  "fixed": "1df42be305fe478ded1ee0c1d775f4ece713483b"
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                  "fixed": "c46cd6aaca81040deaea3500ba75126963294bd9"
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          "database_specific": {
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        {
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              "type": "ECOSYSTEM",
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                  "introduced": "4.7.0"
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            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-46763.json"
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      ],
      "modified": "2026-10-28T02:30:21.621547112Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1df42be305fe478ded1ee0c1d775f4ece713483b",
        "https://git.kernel.org/stable/c/231c235d2f7a66f018f172e26ffd47c363f244ef",
        "https://git.kernel.org/stable/c/4494bccb52ffda22ce5a1163a776d970e6229e08",
        "https://git.kernel.org/stable/c/7e4196935069947d8b70b09c1660b67b067e75cb",
        "https://git.kernel.org/stable/c/c46cd6aaca81040deaea3500ba75126963294bd9",
        "https://git.kernel.org/stable/c/d7567f098f54cb53ee3cee1c82e3d0ed9698b6b3",
        "https://lists.debian.org/debian-lts-announce/2024/10/msg00003.html",
        "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/46xxx/CVE-2024-46763.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-46763",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/46xxx/CVE-2024-46763.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-46763",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 487454,
  "published_at": "2024-09-18T07:12:22.666+00:00"
}