CVE-2026-98012

Summary

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

Affected Software

VendorProductVersion RangeStatus
LinuxLinux82bd38bd5467ece1ee274b493f51326cf5220a5a < f3820dce042a673fcb28cc31c87ee14257e21a17affected
LinuxLinuxe4650d7ae4252f67e997a632adfae0dd74d3a99a < 534cd7ecbbc6e8a974f4003a5c1557439c6e0a72affected
LinuxLinuxe4650d7ae4252f67e997a632adfae0dd74d3a99a < e6c1cb728e389354203a72bc77464c222a247aebaffected
LinuxLinuxe4650d7ae4252f67e997a632adfae0dd74d3a99a < fb9f88a33c516ea5c0bcd9a22ca288b246b34567affected
LinuxLinux843cacb88f42f426973f1ed11c6fb562558efb27affected
LinuxLinux4919649699c5f4dbae08b8e2ed536fc9d6c3c2aaaffected
LinuxLinux548cf048b426729a7a1fa6acd1271c010c9a7380affected
LinuxLinuxc49ac48fac51a6a54efd5963954d02bacf075085affected
LinuxLinux58ae7465f0e7113d45aa88a66bf2d203c71c195eaffected
LinuxLinux6.12.13 < 6.12.111affected
LinuxLinux5.4.297 < 5.5affected
LinuxLinux5.10.239 < 5.11affected
LinuxLinux5.15.186 < 5.16affected
LinuxLinux6.1.129 < 6.2affected
LinuxLinux6.6.76 < 6.7affected
LinuxLinux6.13affected
LinuxLinux0 < 6.13unaffected
LinuxLinux6.12.111 <= 6.12.*unaffected
LinuxLinux6.18.53 <= 6.18.*unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc3 <= *unaffected

Weaknesses

References