Linux Kernel Ftrace Memory Over-Allocation Vulnerability

A vulnerability in the Linux kernel's ftrace functionality can lead to memory over-allocation. The issue arises because the calculation of remaining pages in the ftrace process locations function underestimates the actual capacity of allocated pages, especially when the page size is not a multiple of the entry size. This miscalculation can cause the ftrace system to skip more entries than it should, triggering warnings about the discrepancy. The problem can also occur in another ftrace function responsible for allocating records, potentially leading to further warnings about skipped entries.

Impact

The vulnerability can cause the ftrace system to allocate excess memory, which may lead to inefficient memory usage or exhaustion of available resources.

Reproduction

The vulnerability can be reproduced by allocating a high number of pages in an environment where the page size is not a multiple of the entry size. This can be done by configuring the kernel to use a non-standard entry size and then triggering ftrace to process locations or allocate records, which will result in the over-allocation issue being exposed.

Remediation

Users can upgrade to the patched version of the Linux kernel available in the Linux kernel stable tree.