Memory Overflow Vulnerability in Linux Kernel's S390 Architecture

CVE-2025-38257

What is CVE-2025-38257?

A vulnerability in the s390/pkey module of the Linux kernel has been identified, where the size calculation for memory duplication via the memdup_user() function can overflow. This occurs due to improper handling of the 'nr_apqns' variable, which is determined by user input through an ioctl call. When the calculated size exceeds the allocated buffer, it leads to a mismatch between the actual size and the expected value, resulting in potential unpredictable behavior within the system. To mitigate this issue, the implementation of a safer memdup_array_user() helper is recommended, which correctly checks for overflow conditions.

References