Out-of-Bounds Read in 8cc Compiler

Executive Summary

The vulnerability in 8cc is an Out-of-Bounds Read caused by improper handling of #line directives and GNU linemarkers. The compiler accepts filename and line number metadata that can be controlled by an attacker. It then uses this metadata without proper validation when accessing source line arrays.

By supplying invalid or oversized line numbers, an attacker can cause the compiler to read memory outside the intended bounds, which can lead to a crash.

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Impact Analysis

This vulnerability can cause the 8cc compiler to crash due to out-of-bounds memory access when processing maliciously crafted source code with manipulated #line directives.

While the impact is primarily a denial of service through a crash, it may also pose risks if exploited in a broader context where memory corruption could lead to further security issues.

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Mitigation Strategies

The vulnerability exists in the 8cc compiler due to improper handling of #line directives and GNU linemarkers, which can cause out-of-bounds memory access and crashes.

Since the maintainer has not provided details or a fixed version, and the project is no longer actively maintained, immediate mitigation steps include:

• Avoid using the vulnerable version of 8cc (including the version corresponding to commit b480958) in your environment.
• Consider switching to a maintained alternative compiler such as chibicc, the successor to 8cc.
• If you must use 8cc, restrict input to trusted sources to prevent attacker-controlled filename and line number metadata.
• Monitor for any updates or patches from the community or related projects.

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