CVE-2026-98012

In the Linux kernel, the following vulnerability has been resolved: net/sched: sfq: clamp quantum in change path sfq_change() accepts any non-negative quantum (only rejects (int)ctl->quantum < 0). 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, ...) matching fq_codel_change(). Reject quantum > 1<<20 with -EINVAL, matching fq_codel_change() and the init clamp. Conditions to recreate the bug: CONFIG_NET_SCH_SFQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root sfq tc qdisc change dev dummy0 root sfq quantum 1 stab data 32768 size_log 15 cell_log 0

• https://git.kernel.org/stable/c/0692ce5a528df450d64e9f819054177e9d91076f
• https://git.kernel.org/stable/c/4117c528b2de5fdc3e4a7e3626815b616a635cdc
• https://git.kernel.org/stable/c/534cd7ecbbc6e8a974f4003a5c1557439c6e0a72
• https://git.kernel.org/stable/c/e4192bcf83aaab02129644ddf4656fd86e93751f
• https://git.kernel.org/stable/c/e6c1cb728e389354203a72bc77464c222a247aeb
• https://git.kernel.org/stable/c/f3820dce042a673fcb28cc31c87ee14257e21a17
• https://git.kernel.org/stable/c/f82fa6f10d4a69322cad0f7a4aa523ce6292a5a0
• https://git.kernel.org/stable/c/fb9f88a33c516ea5c0bcd9a22ca288b246b34567