Linux Kernel CSD Lock Vulnerability in Sparse Memory Handling

A vulnerability in the Linux kernel's handling of the csdlock_debug boot parameter has been addressed. The issue arises when the parameter is parsed by the early_param() function, enabling the csd_lock_wait feature. This feature causes a kernel panic on arm64 systems with specific configuration options. The root of the problem lies in a NULL dereference caused by the timing of the parameter parsing, which occurs before the necessary memory sections are initialized. This vulnerability also affects powerpc architectures for similar reasons.

Impact

The vulnerability leads to a NULL pointer dereference, causing a kernel panic.