CVE-2025-38193

Summary

In the Linux kernel, the following vulnerability has been resolved:

net_sched: sch_sfq: reject invalid perturb period

Gerrard Tai reported that SFQ perturb_period has no range check yet, and this can be used to trigger a race condition fixed in a separate patch.

We want to make sure ctl->perturb_period * HZ will not overflow and is positive.

tc qd add dev lo root sfq perturb -10 # negative value : error Error: sch_sfq: invalid perturb period.

tc qd add dev lo root sfq perturb 1000000000 # too big : error Error: sch_sfq: invalid perturb period.

tc qd add dev lo root sfq perturb 2000000 # acceptable value tc -s -d qd sh dev lo qdisc sfq 8005: root refcnt 2 limit 127p quantum 64Kb depth 127 flows 128 divisor 1024 perturb 2000000sec Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0

Affected Software

Weaknesses

ADP Enrichment

CVE Program Container

Additional References

• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

References

• https://git.kernel.org/stable/c/e0936ff56be4e08ad5b60ec26971eae0c40af305
• https://git.kernel.org/stable/c/2254d038dab9c194fe6a4b1ce31034f42e91a6e5
• https://git.kernel.org/stable/c/956b5aebb349449b38d920d444ca1392d43719d1
• https://git.kernel.org/stable/c/b11a50544af691b787384089b68f740ae20a441b
• https://git.kernel.org/stable/c/0357da9149eac621f39e235a135ebf155f01f7c3
• https://git.kernel.org/stable/c/f9b97d466e6026ccbdda30bb5b71965b67ccbc82
• https://git.kernel.org/stable/c/590b2d7d0beadba2aa576708a05a05f0aae39295
• https://git.kernel.org/stable/c/7ca52541c05c832d32b112274f81a985101f9ba8

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