CVE-2026-98010

Summary

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

Affected Software

VendorProductVersion RangeStatus
LinuxLinux13d2a1d2b032de08d7dcab6a1edcd47802681f96 < dc8b374214ef5bba4882bbd95b361e42555cfc0daffected
LinuxLinux13d2a1d2b032de08d7dcab6a1edcd47802681f96 < d43cded350fe1218493ad3d37a276aff14108ae6affected
LinuxLinux13d2a1d2b032de08d7dcab6a1edcd47802681f96 < 8f756ae1c87414ce9cc21b30e6e4c036d6e9e80baffected
LinuxLinux13d2a1d2b032de08d7dcab6a1edcd47802681f96 < 8382abec0f1568d0a5590d75a3df92f23fcf5196affected
LinuxLinux2.6.29affected
LinuxLinux0 < 2.6.29unaffected
LinuxLinux6.12.111 <= 6.12.*unaffected
LinuxLinux6.18.53 <= 6.18.*unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc3 <= *unaffected

Weaknesses

References