net/sched: fq: clamp quantum and initial_quantum in change path

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-90050
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:16:53 UTC
Updated2026-09-17 17:16:53 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: fq: clamp quantum and initial_quantum in change path The fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and TCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to [1, 1<<20]. A user can override the init clamp via tc qdisc change, restoring the small-quantum deficit spin that the init clamp prevents. Narrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at parse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and fq_init() quantum to [256, 1<<20] for tiny-MTU devices. Conditions to recreate the bug: CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root fq tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d16dac3925be95ad46e986d4b139c9898b6e227f a27498d34c3f429fb6db3aa609569f8154afa175 git Not specified
CNA Linux Linux affected f6b3e3848a5fca63438984acd6d9eceac80814c1 798283cd0fe7ba997f67e5a917f14ab40afa8d9f git Not specified
CNA Linux Linux affected e35acd56f244d94355f9ab237c2ecc8fba5e6f04 72e9387884554f47b03bfd40fb8b2bf52789c68d git Not specified
CNA Linux Linux affected 709f34f7c28dc4dd6c40343d101850f11e172312 094cc07f98dfe70a34e2a1923af17fd29b8cf622 git Not specified
CNA Linux Linux affected 7.3-rc1 Not specified
CNA Linux Linux unaffected 7.3-rc1 semver Not specified
CNA Linux Linux unaffected 7.3-rc3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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