CVE-2024-41021 s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()

Medium 5.5 Published 29 Jul 2024 Updated 11 May 2026

A missing check for hardware poison faults on s390 architecture causes a kernel BUG, leading to a system crash and denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2024-41021?

CVE-2024-41021 is a medium-severity denial of service vulnerability in Linux kernel, published on 29 Jul 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()

There is no support for HWPOISON, MEMORY_FAILURE, or ARCH_HAS_COPY_MC on s390. Therefore we do not expect to see VM_FAULT_HWPOISON in do_exception().

However, since commit af19487f00f3 ("mm: make PTE_MARKER_SWAPIN_ERROR more general"), it is possible to see VM_FAULT_HWPOISON in combination with PTE_MARKER_POISONED, even on architectures that do not support HWPOISON otherwise. In this case, we will end up on the BUG() in do_exception().

Fix this by treating VM_FAULT_HWPOISON the same as VM_FAULT_SIGBUS, similar to x86 when MEMORY_FAILURE is not configured. Also print unexpected fault flags, for easier debugging.

Note that VM_FAULT_HWPOISON_LARGE is not expected, because s390 cannot support swap entries on other levels than PTE level.

Weakness: CWE-401

Which versions are affected by CVE-2024-41021?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-41021?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-41021 being exploited?

There is no known exploitation of CVE-2024-41021 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2024-41021, DEBIAN-CVE-2024-41021, GHSA-mm8h-h7mm-pwwr, UBUNTU-CVE-2024-41021.