A flaw was identified in the interactive shell of the xmllint utility, part of the libxml2 project, where memory allocated for user input is not properly released under certain conditions. When a user submits input consisting only of whitespace, the program skips command execution but fails to free the allocated buffer. Repeating this action causes memory to continuously accumulate. Over time, this can exhaust system memory and terminate the xmllint process, creating a denial-of-service condition on the local system.
Weakness
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
Potential Mitigations
- Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
- For example, glibc in Linux provides protection against free of invalid pointers.
- When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
- To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.