CVE-2025-38563 Affecting kernel-rt-modules-core package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL9-KERNELRTMODULESCORE-12072627
  • published21 Aug 2025
  • disclosed19 Aug 2025

Introduced: 19 Aug 2025

NewCVE-2025-38563  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-rt-modules-core.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-modules-core package and not the kernel-rt-modules-core package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

perf/core: Prevent VMA split of buffer mappings

The perf mmap code is careful about mmap()'ing the user page with the ringbuffer and additionally the auxiliary buffer, when the event supports it. Once the first mapping is established, subsequent mapping have to use the same offset and the same size in both cases. The reference counting for the ringbuffer and the auxiliary buffer depends on this being correct.

Though perf does not prevent that a related mapping is split via mmap(2), munmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls, which take reference counts, but then the subsequent perf_mmap_close() calls are not longer fulfilling the offset and size checks. This leads to reference count leaks.

As perf already has the requirement for subsequent mappings to match the initial mapping, the obvious consequence is that VMA splits, caused by resizing of a mapping or partial unmapping, have to be prevented.

Implement the vm_operations_struct::may_split() callback and return unconditionally -EINVAL.

That ensures that the mapping offsets and sizes cannot be changed after the fact. Remapping to a different fixed address with the same size is still possible as it takes the references for the new mapping and drops those of the old mapping.

CVSS Base Scores

version 3.1