CVE-2012-2673 in Garbage Collector
Summary
by MITRE
Multiple integer overflows in the (1) GC_generic_malloc and (2) calloc funtions in malloc.c, and the (3) GC_generic_malloc_ignore_off_page function in mallocx.c in Boehm-Demers-Weiser GC (libgc) before 7.2 make it easier for context-dependent attackers to perform memory-related attacks such as buffer overflows via a large size value, which causes less memory to be allocated than expected.
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Analysis
by VulDB Data Team • 12/31/2024
The Boehm-Demers-Weiser garbage collector represents a widely deployed memory management library that provides automatic memory allocation and deallocation for applications written in C and C++. This library serves as a critical component in numerous software systems, particularly those written in languages such as Scheme, Ocaml, and various scripting environments. The vulnerability under analysis affects versions prior to 7.2 of this library, creating a significant security risk due to integer overflow conditions that can be exploited by attackers to manipulate memory allocation behavior.
The specific vulnerability manifests in three distinct functions within the memory management system: GC_generic_malloc, calloc, and GC_generic_malloc_ignore_off_page. These functions operate at the core of memory allocation operations, where integer overflows occur when processing large size values passed to these functions. The overflow conditions result in scenarios where the system allocates less memory than anticipated, creating a situation where subsequent memory operations may overwrite adjacent memory regions. This fundamental flaw in the integer arithmetic handling within the allocation functions creates a pathway for attackers to manipulate the memory layout of applications using the library.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables attackers to perform sophisticated memory-related attacks including buffer overflows and potentially arbitrary code execution. When an attacker provides a carefully crafted large size value, the integer overflow causes the allocation functions to compute a smaller memory block size than requested, leading to insufficient memory being allocated for legitimate data structures. This creates opportunities for attackers to overwrite adjacent memory regions, potentially corrupting program state, manipulating pointers, or injecting malicious code into the application's memory space.
The exploitation of this vulnerability aligns with several attack patterns documented in the attack tree framework, particularly those involving memory corruption techniques that leverage integer overflows to manipulate program behavior. This vulnerability specifically relates to CWE-190, Integer Overflow or Wraparound, and CWE-121, Stack-based Buffer Overflow, as the integer overflows directly lead to insufficient memory allocation and potential buffer overflows in the affected applications. The context-dependent nature of the attack means that exploitation requires specific conditions related to the size values being passed to the allocation functions, making it less trivial to exploit but still highly dangerous when successful.
Mitigation strategies for this vulnerability involve updating to version 7.2 or later of the Boehm-Demers-Weiser garbage collector, which includes proper integer overflow checks and handling in the affected functions. Organizations should also implement comprehensive code review processes to identify other potential integer overflow conditions in their own codebases, particularly in memory management routines. Additionally, deployment of address space layout randomization, stack canaries, and other memory protection mechanisms can provide additional defense-in-depth layers against exploitation attempts. The vulnerability demonstrates the critical importance of proper integer arithmetic handling in memory management systems and underscores the need for thorough security testing of core library components that form the foundation of application security.