CVE-2024-41021

/// Technical 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.

/// 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