CVE-2025-40245

Technical Description

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

nios2: ensure that memblock.current_limit is set when setting pfn limits

On nios2, with CONFIG_FLATMEM set, the kernel relies on

memblock_get_current_limit() to determine the limits of mem_map, in

particular for max_low_pfn.

Unfortunately, memblock.current_limit is only default initialized to

MEMBLOCK_ALLOC_ANYWHERE at this point of the bootup, potentially leading

to situations where max_low_pfn can erroneously exceed the value of

max_pfn and, thus, the valid range of available DRAM.

This can in turn cause kernel-level paging failures, e.g.:

[ 76.900000] Unable to handle kernel paging request at virtual address 20303000

[ 76.900000] ea = c0080890, ra = c000462c, cause = 14

[ 76.900000] Kernel panic - not syncing: Oops

[ 76.900000] ---[ end Kernel panic - not syncing: Oops ]---

This patch fixes this by pre-calculating memblock.current_limit

based on the upper limits of the available memory ranges via

adjust

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