CVE-2026-90073 (GCVE-0-2026-90073)
Vulnerability from cvelistv5
Published
2026-09-17 16:05
Modified
2026-10-19 08:57
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: hhf: clamp quantum before hhf_change() to avoid overflow hhf_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) with no overflow check. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes weight * quantum overflow the signed deficit in hhf_dequeue(), spinning forever. Clamp q->quantum before hhf_change() so both the opt and !opt paths see a sane quantum. Without this, bare "tc qdisc add ... hhf" succeeds with a clamped quantum but "tc qdisc add ... hhf limit 1000" (any option present) fails with -EINVAL because hhf_change() re-validates the unclamped default (sch_hhf.c:559). 256 matches fq_codel's floor and is a sane minimum for a DRR quantum. Conditions to recreate the bug: a device whose MTU (plus hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.
References
Impacted products
Vendor Product Version
Linux Linux Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
Version: 10239edf86f137ce4c39b62ea9575e8053c549a0
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{
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          "product": "Linux",
          "programFiles": [
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      "cpeApplicability": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: clamp quantum before hhf_change() to avoid overflow\n\nhhf_init() sets q-\u003equantum = psched_mtu(qdisc_dev(sch)) with no overflow\ncheck. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting\nMTU 2147483634) makes weight * quantum overflow the signed deficit in\nhhf_dequeue(), spinning forever.\n\nClamp q-\u003equantum before hhf_change() so both the opt and !opt paths see\na sane quantum. Without this, bare \"tc qdisc add ... hhf\" succeeds with\na clamped quantum but \"tc qdisc add ... hhf limit 1000\" (any option\npresent) fails with -EINVAL because hhf_change() re-validates the\nunclamped default (sch_hhf.c:559). 256 matches fq_codel\u0027s floor and is\na sane minimum for a DRR quantum.\n\nConditions to recreate the bug: a device whose MTU (plus\nhard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy\ndevice with max_mtu == 0 accepting MTU 2147483634). Requires\nCAP_NET_ADMIN in a user namespace."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:30.227Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2e0f0729f922c8de13801004e2131b57646c7c5f"
        },
        {
          "url": "https://git.kernel.org/stable/c/0c66223e90ddb4fd3700965a9241f2fde7bd6bc7"
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        {
          "url": "https://git.kernel.org/stable/c/20b65bf7ca06e48ec1d62ed8012f71205328dbe4"
        },
        {
          "url": "https://git.kernel.org/stable/c/dea2789a9d5ff38bdd77f2e64d550430899e2839"
        },
        {
          "url": "https://git.kernel.org/stable/c/fa9c2055f0a60f801ccf286af53d387dc6202c3f"
        },
        {
          "url": "https://git.kernel.org/stable/c/99770b5d8e0e1c69b996f74a19d71afd2c4a9aa4"
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        {
          "url": "https://git.kernel.org/stable/c/2446644b0f6d045b01db6acbaf55552dbec8a59a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2164b512b97bb053e8ce4d6e95576f11bed6a005"
        }
      ],
      "title": "net/sched: hhf: clamp quantum before hhf_change() to avoid overflow",
      "x_generator": {
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90073",
    "datePublished": "2026-09-17T16:05:53.562Z",
    "dateReserved": "2026-09-11T19:38:34.785Z",
    "dateUpdated": "2026-10-19T08:57:30.227Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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