CVE-2019-20382

QEMU 4.1.0 has a memory leak in zrle_compress_data in ui/vnc-enc-zrle.c during a VNC disconnect operation because libz is misused, resulting in a situation where memory allocated in deflateInit2 is not freed in deflateEnd.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Affected Software

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.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00007.html
• http://www.openwall.com/lists/oss-security/2020/03/05/1
• https://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=6bf21f3d83e95bcc4ba35a7a07cc6655e8b010b0
• https://lists.debian.org/debian-lts-announce/2020/07/msg00020.html
• https://usn.ubuntu.com/4372-1/
• https://www.debian.org/security/2020/dsa-4665