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
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.18-modules-extraUpgrade kernel6.18-debuginfo-common-aarch64Upgrade kernel6.12-modules-extraUpgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel-livepatch-6.12.111-136.204Upgrade bpftool6.12-debuginfoUpgrade perf6.18-debuginfoUpgrade perf6.12Upgrade kernel6.18-debuginfo-common-x86_64Upgrade kernel6.12-debuginfoUpgrade kernel6.12-tools-debuginfoUpgrade kernel6.12-modules-extra-commonUpgrade kernel6.12-tools-develUpgrade python3-perf6.18Upgrade kernel6.18-develUpgrade kernel6.18-tools-debuginfoUpgrade microvm-kernel6.18Upgrade kernel6.18-modules-extra-commonUpgrade python3-perf6.12-debuginfoUpgrade bpftool6.18Upgrade kernel6.12-toolsUpgrade kernel6.12-debuginfo-common-x86_64Upgrade python3-perf6.18-debuginfoUpgrade perf6.18Upgrade kernel6.18-tools-develUpgrade kernel6.12-headersUpgrade kernel6.18Upgrade bpftool6.18-debuginfoUpgrade kernel6.18-debuginfoUpgrade kernel-livepatch-6.18.54-121.166Upgrade kernel6.18-toolsUpgrade kernel6.12Upgrade python3-perf6.12Upgrade kernel6.12-develUpgrade kernel6.18-headersUpgrade bpftool6.12Upgrade perf6.12-debuginfo | Oct 13, 2026 | Sep 25, 2026 |
| Debian | — | Upgrade linux-6.12Upgrade linux | Sep 30, 2026 | Sep 25, 2026 |
| Redhat_linux | — | No solution exists | Sep 30, 2026 | Sep 25, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 13, 2026 | Sep 25, 2026 |
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