CVE-2024-50141

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

ACPI: PRM: Find EFI_MEMORY_RUNTIME block for PRM handler and context

PRMT needs to find the correct type of block to translate the PA-VA

mapping for EFI runtime services.

The issue arises because the PRMT is finding a block of type

EFI_CONVENTIONAL_MEMORY, which is not appropriate for runtime services

as described in Section 2.2.2 (Runtime Services) of the UEFI

Specification [1]. Since the PRM handler is a type of runtime service,

this causes an exception when the PRM handler is called.

[Firmware Bug]: Unable to handle paging request in EFI runtime service

WARNING: CPU: 22 PID: 4330 at drivers/firmware/efi/runtime-wrappers.c:341

__efi_queue_work+0x11c/0x170

Call trace:

Let PRMT find a block with EFI_MEMORY_RUNTIME for PRM handler and PRM

context.

If no suitable block is found, a warning message will be printed, but

the procedure continues to manage the next PRM handler.

However, if the PRM handler is actually called without proper allocation,

it would result in a failure during error handling.

By using the correct memory types for runtime services, ensure that the

PRM handler and the context are properly mapped in the virtual address

space during runtime, preventing the paging request error.

The issue is really that only memory that has been remapped for runtime

by the firmware can be used by the PRM handler, and so the region needs

to have the EFI_MEMORY_RUNTIME attribute.

[ rjw: Subject and changelog edits ]