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CVE-2026-90050

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

In 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
Daten sind bereitgestellt durch das CVE Programm von einer CVE Numbering Authority (CNA) (Unstrukturiert).
HerstellerLinux
≫
Produkt Linux
Default Statusunaffected
Version d16dac3925be95ad46e986d4b139c9898b6e227f
Version < a27498d34c3f429fb6db3aa609569f8154afa175
Status affected
Version f6b3e3848a5fca63438984acd6d9eceac80814c1
Version < 798283cd0fe7ba997f67e5a917f14ab40afa8d9f
Status affected
Version e35acd56f244d94355f9ab237c2ecc8fba5e6f04
Version < 72e9387884554f47b03bfd40fb8b2bf52789c68d
Status affected
Version 709f34f7c28dc4dd6c40343d101850f11e172312
Version < 094cc07f98dfe70a34e2a1923af17fd29b8cf622
Status affected
HerstellerLinux
≫
Produkt Linux
Default Statusaffected
Version 7.3-rc1
Status affected
Version 0
Version < 7.3-rc1
Status unaffected
Version <= *
Version 7.3-rc3
Status unaffected
VulnDex Vulnerability Enrichment
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.2% 0.101
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
Es wurden noch keine Informationen zu CWE veröffentlicht.
https://git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175
https://git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f
https://git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d
https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622