netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()

{
  "id": "4e9cc964239eca7c61bd17e6d69b9ee6654e8e6fb34586a99b3095b54c388a7d",
  "url": "https://osv.dev/vulnerability/CVE-2024-50256",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6() I got a syzbot report without a repro [1] crashing in nf_send_reset6() I think the issue is that dev->hard_header_len is zero, and we attempt later to push an Ethernet header. Use LL_MAX_HEADER, as other functions in net/ipv6/netfilter/nf_reject_ipv6.c. [1] skbuff: skb_under_panic: text:ffffffff89b1d008 len:74 put:14 head:ffff88803123aa00 data:ffff88803123a9f2 tail:0x3c end:0x140 dev:syz_tun kernel BUG at net/core/skbuff.c:206 ! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 UID: 0 PID: 7373 Comm: syz.1.568 Not tainted 6.12.0-rc2-syzkaller-00631-g6d858708d465 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:skb_panic net/core/skbuff.c:206 [inline] RIP: 0010:skb_under_panic+0x14b/0x150 net/core/skbuff.c:216 Code: 0d 8d 48 c7 c6 60 a6 29 8e 48 8b 54 24 08 8b 0c 24 44 8b 44 24 04 4d 89 e9 50 41 54 41 57 41 56 e8 ba 30 38 02 48 83 c4 20 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 RSP: 0018:ffffc900045269b0 EFLAGS: 00010282 RAX: 0000000000000088 RBX: dffffc0000000000 RCX: cd66dacdc5d8e800 RDX: 0000000000000000 RSI: 0000000000000200 RDI: 0000000000000000 RBP: ffff88802d39a3d0 R08: ffffffff8174afec R09: 1ffff920008a4ccc R10: dffffc0000000000 R11: fffff520008a4ccd R12: 0000000000000140 R13: ffff88803123aa00 R14: ffff88803123a9f2 R15: 000000000000003c FS: 000",
    "evidence": "osv:CVE-2024-50256",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.116",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.60",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.11.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2024-50256",
      "aliases": [
        "CVE-2024-50256"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "c8d7b98bec43faaa6583c3135030be5eb4693acb"
                },
                {
                  "fixed": "4f7b586aae53c2ed820661803da8ce18b1361921"
                },
                {
                  "fixed": "fef63832317d9d24e1214cdd8f204d02ebdf8499"
                },
                {
                  "fixed": "f85b057e34419e5ec0583a65078a11ccc1d4540a"
                },
                {
                  "fixed": "4ed234fe793f27a3b151c43d2106df2ff0d81aac"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-50256.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "3.18.0"
                },
                {
                  "fixed": "6.1.116"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.60"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.11.7"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-50256.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.185372387Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/4ed234fe793f27a3b151c43d2106df2ff0d81aac",
        "https://git.kernel.org/stable/c/4f7b586aae53c2ed820661803da8ce18b1361921",
        "https://git.kernel.org/stable/c/f85b057e34419e5ec0583a65078a11ccc1d4540a",
        "https://git.kernel.org/stable/c/fef63832317d9d24e1214cdd8f204d02ebdf8499",
        "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/50xxx/CVE-2024-50256.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-50256",
        "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/2024/50xxx/CVE-2024-50256.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-50256",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518217,
  "published_at": "2024-11-09T10:15:09.551+00:00"
}