Linux Kernel MIPS Ftrace Memory Corruption Vulnerability

A memory corruption vulnerability has been identified in the Linux kernel's MIPS architecture, specifically within the ftrace component. This issue arises when the kernel is located beyond 32 bits, leading to a buffer overflow. The problem was introduced in a previous commit that aimed to reduce the overhead of dynamic function tracing. The ftrace code incorrectly assumes that certain macros will generate no more than two instructions, which is not the case, causing corruption of variables in the __read_mostly section. This corruption was evident as it disrupted the __cpu_primary_thread_mask variable, leading to a system hang early in the boot process. The vulnerability has been addressed by modifying the instruction generation process to prevent exceeding the two-instruction limit, although this restricts the use of dynamic ftrace in some scenarios.

Impact

The vulnerability causes memory corruption that can disrupt kernel operations, specifically by corrupting variables essential for thread management, leading to system hangs during boot.

Remediation

Users can apply the latest patches available in the Linux kernel stable tree to address this vulnerability.