net/sched: ets: clamp quantum in parse and fallback paths

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: ets: clamp quantum in parse and fallback paths ets_qdisc_change() falls back to psched_mtu() with no floor for bands without an explicit quantum. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so a zero psched_mtu on a headerless device makes the deficit-refill loop spin under the qdisc lock. Move the floor into ets_quantum_parse() so explicitly configured quanta are also clamped to [256, 1<<20], not just the fallback path. Conditions to recreate the bug: CONFIG_NET_SCH_ETS=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root ets bands 3 strict 2 quanta 1 1

Timeline

1. Sep 25, 2026, 10:23 AM UTCCVE published
2. Oct 19, 2026, 9:12 AM UTCRecord last updated

Affected versions

• Linux Linux

  From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 440b66cc7b56ea38e9b878ae88da91992efaa4c4; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 4ef8664eafafc8db68a1d52601f17dc008a223b7; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 8b8d782c3b96376217087767dcf662cd3d25f226; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 226d2702e74a570f5bfae6115b4706da4b94e5cf; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 99ae477b892e203a37985ebc56f0063e072f7f4b; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 8f80b113dea0bed3c1a31a4224b72775cd9ec52d; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in de22c30ec5598aca8797f02082d2ee1358dfa3ff; From dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 · fixed in 1c38487f46b243bfeefec0c0c86023a3904f2214

• Linux Linux

  5.6

• KernelLinux

  From 5.6.0 · fixed in 5.10.271; From 5.11.0 · fixed in 5.15.222; From 5.16.0 · fixed in 6.1.189; From 6.2.0 · fixed in 6.6.158; From 6.7.0 · fixed in 6.12.111; From 6.13.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7

References 8