CVE-2026-98011

Summary

In the Linux kernel, the following vulnerability has been resolved:

net/sched: hhf: clamp quantum in change and init paths

hhf_change() accepts any quantum from userspace, including 1. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times under the qdisc lock (a soft lockup / denial of service).

Add max(256U, …) in hhf_change() matching fq_codel_change(). Clamp hhf_init() to [256, 1<<20] matching the siblings, and remove the old fallback that only set quantum=256 on overflow.

Conditions to recreate the bug: CONFIG_NET_SCH_HHF=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices).

tc qdisc add dev dummy0 root hhf tc qdisc change dev dummy0 root hhf quantum 1 stab data 32768 size_log 15 cell_log 0

Affected Software

VendorProductVersion RangeStatus
LinuxLinux10239edf86f137ce4c39b62ea9575e8053c549a0 < 1113b674307ffddd402524bd1fd9d7d5629b705baffected
LinuxLinux10239edf86f137ce4c39b62ea9575e8053c549a0 < 2e77947bbf6c166e76c038663832d0914418f761affected
LinuxLinux10239edf86f137ce4c39b62ea9575e8053c549a0 < 0898c6f9fa9ce2632ae88bd0f34a878ccc6335afaffected
LinuxLinux10239edf86f137ce4c39b62ea9575e8053c549a0 < eb56a495f59baf6cad5ed80e3ffb9078098b1346affected
LinuxLinux3.14affected
LinuxLinux0 < 3.14unaffected
LinuxLinux6.12.111 <= 6.12.*unaffected
LinuxLinux6.18.53 <= 6.18.*unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc3 <= *unaffected

Weaknesses

References