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CVE-2025-38563 Detail

Description

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.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/3bd518cc7ea61076bcd725e36ff0e690754977c0 kernel.org
https://git.kernel.org/stable/c/65311aad4c808bedad0c05d9bb8b06c47dae73eb kernel.org
https://git.kernel.org/stable/c/6757a31a8e295ae4f01717a954afda173f25a121 kernel.org
https://git.kernel.org/stable/c/7b84cb58d1f0aa07656802eae24689566e5f5b1b kernel.org
https://git.kernel.org/stable/c/b024d7b56c77191cde544f838debb7f8451cd0d6 kernel.org
https://git.kernel.org/stable/c/d52451a9210f2e5a079ba052918c93563518a9ff kernel.org
https://git.kernel.org/stable/c/e4346ffec2c44d6b0be834d59b20632b5bb5729e kernel.org
https://git.kernel.org/stable/c/e529888b7e8092912dd8789bdfc76685ccd2ff5f kernel.org
https://git.kernel.org/stable/c/ff668930871e0198c7f4e325058b8b7c286787bd kernel.org

Weakness Enumeration

CWE-ID CWE Name Source

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-38563
NVD Published Date:
08/19/2025
NVD Last Modified:
08/28/2025
Source:
kernel.org