vulnerability

Oracle Linux: CVE-2025-38193: ELSA-2025-20552: Unbreakable Enterprise kernel security update (IMPORTANT) (Multiple Advisories)

Severity
4
CVSS
(AV:L/AC:L/Au:M/C:N/I:N/A:C)
Published
Jul 4, 2025
Added
Sep 10, 2025
Modified
Feb 11, 2026

Description

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

Solution

oracle-linux-upgrade-kernel-uek
Title
NEW

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