Linux Kernel s390 Current Stack Pointer Vulnerability Stack Corruption

A vulnerability in the Linux kernel on the s390 architecture has been addressed. The issue arose because a recent commit made the current stack pointer a global register variable, similar to other architectures. This change exposed a long-standing bug in GCC that could lead to stack corruption, as certain older GCC versions generated faulty code. The vulnerability is particularly relevant because the minimum required GCC version to build the kernel is 5.1, leaving older versions unfixable. The kernel now avoids using global register variables for the current stack pointer on s390 to prevent these stack corruption issues.

Impact

The vulnerability could lead to stack corruption, potentially allowing for arbitrary code execution or causing other unintended behavior by disrupting the normal stack operations.