net/sched: accept TCA_STAB only for root qdisc

{
  "id": "ec910a1a7bec0c48a21de6e4ac6137a52af4d922f0daaa51f2c8043e298099ca",
  "url": "https://osv.dev/vulnerability/CVE-2024-50039",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/sched: accept TCA_STAB only for root qdisc",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/sched: accept TCA_STAB only for root qdisc Most qdiscs maintain their backlog using qdisc_pkt_len(skb) on the assumption it is invariant between the enqueue() and dequeue() handlers. Unfortunately syzbot can crash a host rather easily using a TBF + SFQ combination, with an STAB on SFQ [1] We can't support TCA_STAB on arbitrary level, this would require to maintain per-qdisc storage. [1] [ 88.796496] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 88.798611] #PF: supervisor read access in kernel mode [ 88.799014] #PF: error_code(0x0000) - not-present page [ 88.799506] PGD 0 P4D 0 [ 88.799829] Oops: Oops: 0000 [#1] SMP NOPTI [ 88.800569] CPU: 14 UID: 0 PID: 2053 Comm: b371744477 Not tainted 6.12.0-rc1-virtme #1117 [ 88.801107] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 88.801779] RIP: 0010:sfq_dequeue (net/sched/sch_sfq.c:272 net/sched/sch_sfq.c:499) sch_sfq [ 88.802544] Code: 0f b7 50 12 48 8d 04 d5 00 00 00 00 48 89 d6 48 29 d0 48 8b 91 c0 01 00 00 48 c1 e0 03 48 01 c2 66 83 7a 1a 00 7e c0 48 8b 3a <4c> 8b 07 4c 89 02 49 89 50 08 48 c7 47 08 00 00 00 00 48 c7 07 00 All code ======== 0: 0f b7 50 12 movzwl 0x12(%rax),%edx 4: 48 8d 04 d5 00 00 00 lea 0x0(,%rdx,8),%rax b: 00 c: 48 89 d6 mov %rdx,%rsi f: 48 29 d0 sub %rdx,%rax 12: 48 8b 91 c0 01 00 00 mov 0x1c0(%rcx),%rdx 19: 48 c1 e0 03 shl $0x3,%rax 1d: 48 01 c2 add %rax,%rdx 20: 66 83 7a",
    "evidence": "osv:CVE-2024-50039",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.4.285",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.10.227",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.168",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.113",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.57",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.11.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2024-50039",
      "aliases": [
        "CVE-2024-50039"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "175f9c1bba9b825d22b142d183c9e175488b260c"
                },
                {
                  "fixed": "2acbb9539bc2284e30d2aeb789c3d96287014264"
                },
                {
                  "fixed": "adbc3eef43fc94c7c8436da832691ae02333a972"
                },
                {
                  "fixed": "8fb6503592d39065316f45d267c5527b4e7cd995"
                },
                {
                  "fixed": "76feedc74b90270390fbfdf74a2e944e96872363"
                },
                {
                  "fixed": "1edf039ee01788ffc25625fe58a903ae2efa213e"
                },
                {
                  "fixed": "3dc6ee96473cc2962c6db4297d4631f261be150f"
                },
                {
                  "fixed": "3cb7cf1540ddff5473d6baeb530228d19bc97b8a"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-50039.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "2.6.27"
                },
                {
                  "fixed": "5.4.285"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.5.0"
                },
                {
                  "fixed": "5.10.227"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.168"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.113"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.57"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.11.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-50039.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.303132827Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-265688.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-355557.html",
        "https://git.kernel.org/stable/c/1edf039ee01788ffc25625fe58a903ae2efa213e",
        "https://git.kernel.org/stable/c/2acbb9539bc2284e30d2aeb789c3d96287014264",
        "https://git.kernel.org/stable/c/3cb7cf1540ddff5473d6baeb530228d19bc97b8a",
        "https://git.kernel.org/stable/c/3dc6ee96473cc2962c6db4297d4631f261be150f",
        "https://git.kernel.org/stable/c/76feedc74b90270390fbfdf74a2e944e96872363",
        "https://git.kernel.org/stable/c/8fb6503592d39065316f45d267c5527b4e7cd995",
        "https://git.kernel.org/stable/c/adbc3eef43fc94c7c8436da832691ae02333a972",
        "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/50xxx/CVE-2024-50039.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-50039",
        "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-2024-50039.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-50039",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 493679,
  "published_at": "2024-10-21T19:39:39.115+00:00"
}