FKIE_CVE-2026-90074

Vulnerability from fkie_nvd - Published: 2026-09-17 17:16 - Updated: 2026-09-17 17:16
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: fq_pie: clamp default quantum to avoid signed overflow fq_pie_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without clamping. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return 0x80000000, which overflows the signed flow->deficit to INT_MIN in fq_pie_qdisc_dequeue(), causing an infinite loop and soft lockup. Emulate fq_pie_policy which is already bounded to [1, 1 << 20]; clamp the default to [256, 1 << 20]. 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
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/044fa2498bbc2900f0c48a6ef2fdd5b2bdfc3795
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1f43e4dbc93b7d02761a024d5f895df823c07b72
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/435da3734a8e63d3067016accc977ed1d10aaaa0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/44dad8fe99b58a7fe2961e9eec6a5f07ace5b51f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6f1be05faecef4c0f9a008200209f66ef2e133f7
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bf97fd2163ad1191ef8daa3d4df8372aee19e396
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c86cd7ed0b0e44779a3d1683f03e4353baf4bdc9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f7942b2693bc24c7d609a03d06f97bee3b0bd96a
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_fq_pie.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1f43e4dbc93b7d02761a024d5f895df823c07b72",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "f7942b2693bc24c7d609a03d06f97bee3b0bd96a",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "6f1be05faecef4c0f9a008200209f66ef2e133f7",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "435da3734a8e63d3067016accc977ed1d10aaaa0",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "44dad8fe99b58a7fe2961e9eec6a5f07ace5b51f",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "044fa2498bbc2900f0c48a6ef2fdd5b2bdfc3795",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "bf97fd2163ad1191ef8daa3d4df8372aee19e396",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            },
            {
              "lessThan": "c86cd7ed0b0e44779a3d1683f03e4353baf4bdc9",
              "status": "affected",
              "version": "ec97ecf1ebe485a17cd8395a5f35e6b80b57665a",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_fq_pie.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.6"
            },
            {
              "lessThan": "5.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq_pie: clamp default quantum to avoid signed overflow\n\nfq_pie_init() sets q-\u003equantum = psched_mtu(qdisc_dev(sch)) without\nclamping. A device with a huge MTU (e.g. dummy with max_mtu == 0\naccepting MTU 2147483634) makes psched_mtu() return 0x80000000, which\noverflows the signed flow-\u003edeficit to INT_MIN in fq_pie_qdisc_dequeue(),\ncausing an infinite loop and soft lockup. Emulate fq_pie_policy which\nis already bounded to [1, 1 \u003c\u003c 20]; clamp the default to [256, 1 \u003c\u003c 20].\n256 matches fq_codel\u0027s floor and is a 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."
    }
  ],
  "id": "CVE-2026-90074",
  "lastModified": "2026-09-17T17:16:56.530",
  "metrics": {},
  "published": "2026-09-17T17:16:56.530",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/044fa2498bbc2900f0c48a6ef2fdd5b2bdfc3795"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1f43e4dbc93b7d02761a024d5f895df823c07b72"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/435da3734a8e63d3067016accc977ed1d10aaaa0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/44dad8fe99b58a7fe2961e9eec6a5f07ace5b51f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6f1be05faecef4c0f9a008200209f66ef2e133f7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bf97fd2163ad1191ef8daa3d4df8372aee19e396"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c86cd7ed0b0e44779a3d1683f03e4353baf4bdc9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f7942b2693bc24c7d609a03d06f97bee3b0bd96a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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