CVE-2025-38563— perf/core: Prevent VMA split of buffer mappings

perf/core: Prevent VMA split of buffer mappings

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.

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Linux kernel 安全漏洞

Linux kernel是美国等都是美国(Linux)基金会的产品。Linux kernel是开源操作系统Linux所使用的内核。ops等都是的产品。ops是一个用于开发和测试 Kubernetes 和 machine charms 的 Python 框架。roc req等都是(roc)个人开发者的产品。req是一个使用 Black Magic 的简单 Go HTTP 客户端。 Linux kernel存在安全漏洞，该漏洞源于未防止VMA分割，可能导致引用计数泄漏。

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