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
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel-livepatch-6.12.111-136.204Upgrade perf6.12-debuginfoUpgrade perf6.18-debuginfoUpgrade kernel6.12-tools-develUpgrade kernel6.18-debuginfo-common-x86_64Upgrade kernel6.18-toolsUpgrade kernel6.18-modules-extraUpgrade bpftool6.12-debuginfoUpgrade kernel6.18Upgrade python3-perf6.12Upgrade kernel6.18-headersUpgrade kernel6.12-modules-extraUpgrade kernel6.12-toolsUpgrade microvm-kernel6.18Upgrade python3-perf6.12-debuginfoUpgrade bpftool6.18-debuginfoUpgrade kernel6.18-debuginfoUpgrade kernel6.18-debuginfo-common-aarch64Upgrade kernel-livepatch-6.18.54-121.166Upgrade kernel6.12Upgrade bpftool6.12Upgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel6.12-modules-extra-commonUpgrade perf6.18Upgrade kernel6.12-tools-debuginfoUpgrade bpftool6.18Upgrade kernel6.12-develUpgrade python3-perf6.18-debuginfoUpgrade kernel6.18-tools-develUpgrade kernel6.18-modules-extra-commonUpgrade kernel6.12-debuginfo-common-x86_64Upgrade kernel6.12-headersUpgrade kernel6.18-tools-debuginfoUpgrade perf6.12Upgrade python3-perf6.18Upgrade kernel6.12-debuginfoUpgrade kernel6.18-devel | 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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