Linux Kernel Integer Overflow Vulnerability in fbcon Component

An integer overflow vulnerability has been identified in the Linux kernel's framebuffer console (fbcon) component, specifically within the fbcon_do_set_font() function. This vulnerability arises from the handling of user-controlled font parameters, which can lead to incorrect memory allocations. The issue occurs when the font size calculation, based on user-defined values, exceeds the maximum limit, causing smaller-than-expected allocations. This flaw can be exploited to overwrite memory boundaries, potentially leading to arbitrary code execution or other malicious outcomes.

Impact

Exploitation of this vulnerability can cause buffer overflows during the copying of font data, allowing for memory corruption that could be exploited to execute arbitrary code.

Reproduction

The vulnerability can be reproduced by invoking the fbcon_set_font function with carefully crafted parameters that cause the font size calculation to overflow. This can be done by manipulating the height, pitch, and character count values, which are used to calculate the font size. The overflow can be exploited by adding additional font data that exceeds the allocated buffer size, causing a buffer overflow.

Remediation

Users can upgrade to the latest version of the Linux kernel, where this vulnerability has been addressed. Instructions for upgrading the kernel can be found in the official Linux kernel documentation.