CVE-2026-43416

/// Technical description

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

powerpc, perf: Check that current->mm is alive before getting user callchain

It may happen that mm is already released, which leads to kernel panic.

This adds the NULL check for current->mm, similarly to

commit 20afc60f892d ("x86, perf: Check that current->mm is alive before getting user callchain").

I was getting this panic when running a profiling BPF program

(profile.py from bcc-tools):

[26215.051935] Kernel attempted to read user page (588) - exploit attempt? (uid: 0)

[26215.051950] BUG: Kernel NULL pointer dereference on read at 0x00000588

[26215.051952] Faulting instruction address: 0xc00000000020fac0

[26215.051957] Oops: Kernel access of bad area, sig: 11 [#1]

[...]

[26215.052049] Call Trace:

[26215.052050] [c000000061da6d30] [c00000000020fc10] perf_callchain_user_64+0x2d0/0x490 (unreliable)

[26215.052054] [c000000061da6dc0] [c00000000020f92c] perf_callchain_user+0x1c/0x30

/// 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