CVE-2025-38424

/// Technical description

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

perf: Fix sample vs do_exit()

Baisheng Gao reported an ARM64 crash, which Mark decoded as being a

synchronous external abort -- most likely due to trying to access

MMIO in bad ways.

The crash further shows perf trying to do a user stack sample while in

exit_mmap()'s tlb_finish_mmu() -- i.e. while tearing down the address

space it is trying to access.

It turns out that we stop perf after we tear down the userspace mm; a

receipie for disaster, since perf likes to access userspace for

various reasons.

Flip this order by moving up where we stop perf in do_exit().

Additionally, harden PERF_SAMPLE_CALLCHAIN and PERF_SAMPLE_STACK_USER

to abort when the current task does not have an mm (exit_mm() makes

sure to set current->mm = NULL; before commencing with the actual

teardown). Such that CPU wide events don't trip on this same problem.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References