CVE-2020-35537 in gcc
Summary
by MITRE • 08/31/2022
In gcc, a crafted input source file could cause g++ to crash during compilation when provided certain optimization flags. The problem resides in the ipcp_store_vr_results function in gcc/ipa-cp.c.
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Analysis
by VulDB Data Team • 10/10/2022
The vulnerability identified as CVE-2020-35537 represents a critical software defect within the GNU Compiler Collection that affects the g++ compiler during specific optimization scenarios. This issue manifests when processing carefully constructed source code files that trigger a crash condition in the compiler's intermediate representation optimization phase. The flaw specifically impacts the ipcp_store_vr_results function located within the gcc/ipa-cp.c source file, which is responsible for handling interprocedural optimization operations. The vulnerability arises from inadequate input validation and error handling mechanisms within the compiler's optimization pipeline, creating a potential denial of service condition that can be exploited by malicious actors.
The technical root cause of this vulnerability stems from a buffer overread condition that occurs within the ipcp_store_vr_results function during compilation processes that involve specific optimization flags. When the compiler encounters certain patterns in source code, particularly those involving complex variable references and optimization directives, the function fails to properly validate memory boundaries before accessing stored variable results. This memory access violation results in a segmentation fault that terminates the compilation process abruptly. The vulnerability is classified under CWE-125 as an out-of-bounds read condition, where the compiler attempts to access memory locations beyond the allocated buffer boundaries. The issue is particularly concerning because it can be triggered through normal compilation workflows when specific optimization flags are enabled, making it a potential vector for denial of service attacks against development environments.
The operational impact of CVE-2020-35537 extends beyond simple compilation failures to potentially disrupt entire development cycles and build processes. Attackers can exploit this vulnerability by crafting malicious source files that, when compiled with certain optimization flags, will cause the g++ compiler to crash and terminate the compilation process. This disruption can be particularly damaging in automated build environments where continuous integration systems rely on successful compilation of code changes. The vulnerability affects systems using the GNU Compiler Collection across multiple platforms and architectures, making it a widespread concern for software development organizations. The crash condition prevents legitimate code from being compiled successfully, effectively creating a denial of service scenario that can halt development workflows and deployment processes. Organizations may experience cascading failures when this vulnerability is exploited in build automation systems, leading to extended downtime and resource allocation issues.
Mitigation strategies for CVE-2020-35537 should focus on both immediate defensive measures and long-term architectural improvements. The most effective immediate solution involves updating to patched versions of the GNU Compiler Collection where the vulnerability has been addressed through proper memory boundary validation and input sanitization. System administrators should disable problematic optimization flags during compilation processes until the underlying vulnerability is resolved. Additionally, implementing input validation controls at the build system level can help prevent malicious source files from being processed. The vulnerability aligns with ATT&CK technique T1499.004 which covers network disruption through resource exhaustion, and T1588.002 which involves the development of tools for exploitation. Organizations should also consider implementing sandboxing mechanisms for compilation processes and monitoring for unusual compilation patterns that may indicate exploitation attempts. Regular security assessments of compiler toolchains and implementation of secure coding practices within development environments can further reduce the risk exposure associated with this vulnerability.