High · published July 3, 2025
In the Linux kernel, the following vulnerability has been resolved:
net_sched: sch_sfq: fix a potential crash on gso_skb handling
SFQ has an assumption of always being able to queue at least one packet.
However, after the blamed commit, sch->q.len can be inflated by packets
in sch->gso_skb, and an enqueue() on an empty SFQ qdisc can be followed
by an immediate drop.
Fix sfq_drop() to properly clear q->tail in this situation.
ip netns add lb
ip link add dev to-lb type veth peer name in-lb netns lb
ethtool -K to-lb tso off # force qdisc to requeue gso_skb
ip netns exec lb ethtool -K in-lb gro on # enable NAPI
ip link set dev to-lb up
ip -netns lb link set dev in-lb up
ip addr add dev to-lb 192.168.20.1/24
ip -netns lb addr add dev in-lb 192.168.20.2/24
tc qdisc replace dev to-lb root sfq limit 100
ip netns exec lb netserver
netperf -H 192.168.20.2 -l 100 &
netperf -H 192.168.20.2 -l 100 &
netperf -H 192.168.20.2 -l 100 &
netperf -H 192.168.20.2 -l 100 &
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 4.16, < 5.4.295 | 5.4.295 |
| linux/linux_kernel | ≥ 5.5, < 5.10.239 | 5.10.239 |
| linux/linux_kernel | ≥ 5.11, < 5.15.186 | 5.15.186 |
| linux/linux_kernel | ≥ 5.16, < 6.1.142 | 6.1.142 |
| linux/linux_kernel | ≥ 6.2, < 6.6.94 | 6.6.94 |
| linux/linux_kernel | ≥ 6.7, < 6.12.34 | 6.12.34 |
| linux/linux_kernel | ≥ 6.13, < 6.15.3 | 6.15.3 |
| linux/linux_kernel | all versions | — |
| debian/debian_linux | all versions | — |