CVE-2026-98010
Summary
by MITRE • 09/25/2026
In the Linux kernel, the following vulnerability has been resolved:
net/sched: drr: clamp quantum in change class
drr_change_class() rejects explicit quantum==0 but falls back to psched_mtu() with no floor. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 (or a zero psched_mtu on a headerless device) makes the deficit-refill loop spin under the qdisc lock.
Add clamp_t(u32, quantum, 256, 1<<20) after the zero reject and on the fallback path. The explicit-zero reject is preserved.
Conditions to recreate the bug: CONFIG_NET_SCH_DRR=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices).
tc qdisc add dev dummy0 root drr tc class add dev dummy0 parent 1: classid 1:1 drr quantum 1
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