ipv6: annotate data-race in ndisc_router_discovery()

{
  "id": "2b4d317c4de9d564285ff5364b4e649c1e84cd545482aa795180b3d5fa68838a",
  "url": "https://osv.dev/vulnerability/CVE-2026-23124",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ipv6: annotate data-race in ndisc_router_discovery()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ipv6: annotate data-race in ndisc_router_discovery() syzbot found that ndisc_router_discovery() could read and write in6_dev->ra_mtu without holding a lock [1] This looks fine, IFLA_INET6_RA_MTU is best effort. Add READ_ONCE()/WRITE_ONCE() to document the race. Note that we might also reject illegal MTU values (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) in a future patch. [1] BUG: KCSAN: data-race in ndisc_router_discovery / ndisc_router_discovery read to 0xffff888119809c20 of 4 bytes by task 25817 on cpu 1: ndisc_router_discovery+0x151d/0x1c90 net/ipv6/ndisc.c:1558 ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841 icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989 ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500 ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590 dst_input include/net/dst.h:474 [inline] ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79 ... write to 0xffff888119809c20 of 4 bytes by task 25816 on cpu 0: ndisc_router_discovery+0x155a/0x1c90 net/ipv6/ndisc.c:1559 ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841 icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989 ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:5",
    "evidence": "osv:CVE-2026-23124",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.199",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.162",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.122",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.68",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-23124",
      "aliases": [
        "CVE-2026-23124"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "2619499169fb1c2ac4974b0f2d87767fb543582b"
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                {
                  "fixed": "fad8f4ff7928f4d52a062ffdcffa484989c79c47"
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                {
                  "fixed": "2a2b9d25f801afecf2f83cacce98afa8fd73e3c9"
                },
                {
                  "fixed": "e3c1040252e598f7b4e33a42dc7c38519bc22428"
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                {
                  "fixed": "9a063f96d87efc3a6cc667f8de096a3d38d74bb5"
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              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23124.json"
          }
        },
        {
          "ranges": [
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              "type": "ECOSYSTEM",
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                  "introduced": "5.15.0"
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                {
                  "fixed": "6.1.162"
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            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
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            {
              "type": "ECOSYSTEM",
              "events": [
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              "type": "ECOSYSTEM",
              "events": [
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23124.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.745589097Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2619499169fb1c2ac4974b0f2d87767fb543582b",
        "https://git.kernel.org/stable/c/2a2b9d25f801afecf2f83cacce98afa8fd73e3c9",
        "https://git.kernel.org/stable/c/4630897eb1a039b5d7b737b8dc9521d9d4b568b5",
        "https://git.kernel.org/stable/c/9a063f96d87efc3a6cc667f8de096a3d38d74bb5",
        "https://git.kernel.org/stable/c/e3c1040252e598f7b4e33a42dc7c38519bc22428",
        "https://git.kernel.org/stable/c/fad8f4ff7928f4d52a062ffdcffa484989c79c47",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23124.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23124",
        "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/2026/23xxx/CVE-2026-23124.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-23124",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 496793,
  "published_at": "2026-02-14T15:09:54.043+00:00"
}