CVE-2024-41021 Information

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.

Reference

https://git.kernel.org/stable/c/9e13767ccefdc4f8aa92514b592b60f6b54882ff https://git.kernel.org/stable/c/a3aefb871222a9880602d1a44a558177b4143e3b https://git.kernel.org/stable/c/df39038cd89525d465c2c8827eb64116873f141a