Linux Kernel RISC-V Linear Mapping Vulnerability Causes Page Fault

A vulnerability in the Linux kernel's RISC-V architecture has been addressed, which involved improper handling of memory block resizing. The issue arose because the initial memory block metadata was accessed from the kernel image mapping, and certain regions needed to be reallocated and accessed through a linear mapping. Resizing memory blocks was not allowed until the linear mapping was established, leading to a page fault when the old array in the kernel image mapping was copied to the new array in the linear mapping. This vulnerability was similar to a previously identified issue in the arm64 architecture.

Impact

The vulnerability could cause a kernel panic by attempting to kill the idle task, disrupting normal system operations.

Reproduction

The vulnerability can be reproduced by reserving multiple memory block regions before the linear mapping is created. This sequence triggers a reallocation of the reserved regions, causing a page fault when the system attempts to access the memory through an invalid mapping.

Remediation

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