CVE-2020-35536 in gcc
Summary
by MITRE • 08/31/2022
In gcc, an internal compiler error in match_reload function at lra-constraints.c may cause a crash through a crafted input file.
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Analysis
by VulDB Data Team • 10/10/2022
The vulnerability identified as CVE-2020-35536 represents a critical internal compiler error within the GNU Compiler Collection that manifests through a specific function in the compiler's optimization pipeline. This issue resides in the match_reload function located within the lra-constraints.c file, which is part of the compiler's loop register allocation system. The flaw occurs during the compilation process when the compiler encounters a specially crafted input file that triggers an unexpected code path within the register allocation constraints handling mechanism.
The technical nature of this vulnerability stems from inadequate input validation and error handling within the compiler's internal algorithms. When the match_reload function processes certain complex constraint patterns, it fails to properly validate the input parameters or handle edge cases that can arise from malformed or maliciously constructed source code. This results in a crash condition that terminates the compiler process before it can complete the compilation task. The vulnerability is classified under CWE-248 as an Uncaught Exception, specifically manifesting as an internal compiler error that disrupts normal program execution flow.
From an operational perspective, this vulnerability poses significant risks to software development environments that rely heavily on automated compilation processes. Attackers could potentially exploit this weakness by submitting crafted source files that trigger the crash condition, leading to denial of service against compilation servers or development workstations. The impact extends beyond simple disruption as it could be leveraged in broader attack scenarios where attackers attempt to compromise build systems or introduce timing-based side-channel information through repeated crash attempts. This vulnerability affects the integrity of the compilation process and could potentially be chained with other weaknesses to achieve more sophisticated attack objectives.
The mitigation strategies for CVE-2020-35536 primarily involve applying the official patches released by the gcc development team, which typically include enhanced input validation and proper error handling within the match_reload function. Organizations should prioritize updating their compiler toolchains to versions that contain the fixed implementation, as this addresses the root cause of the internal compiler error. Additionally, implementing proper input sanitization and validation at the build system level can help prevent malformed source files from reaching the compiler. Security monitoring should include detection of unusual compilation patterns or repeated crash events that might indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1059.008 for Compiler Tool Foundation, where adversaries use compiler vulnerabilities to execute malicious code or disrupt legitimate compilation processes, making it a significant concern for secure software development practices.