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Fencer Vulns
medium 5.5

CVE-2025-38522 json

sched/ext: Prevent update_locked_rq() calls with NULL rq

published 2025-08-16 14 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-27881

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

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

sched/ext: Prevent update_locked_rq() calls with NULL rq

Avoid invoking update_locked_rq() when the runqueue (rq) pointer is NULL in the SCX_CALL_OP and SCX_CALL_OP_RET macros.

Previously, calling update_locked_rq(NULL) with preemption enabled could trigger the following warning:

BUG: using __this_cpu_write() in preemptible [00000000]

This happens because __this_cpu_write() is unsafe to use in preemptible context.

rq is NULL when an ops invoked from an unlocked context. In such cases, we don't need to store any rq, since the value should already be NULL (unlocked). Ensure that update_locked_rq() is only called when rq is non-NULL, preventing calling __this_cpu_write() on preemptible context.

Patch / fix

  • Linux Linux 6.15.8, 6.16

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-38522 updated

kernel: sched/ext: Prevent update_locked_rq() calls with NULL rq

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.