CVE-2016-10163 in QEMU
Summary
by MITRE
Memory leak in the vrend_renderer_context_create_internal function in vrend_decode.c in virglrenderer before 0.6.0 allows local guest OS users to cause a denial of service (host memory consumption) by repeatedly creating a decode context.
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Analysis
by VulDB Data Team • 04/25/2020
The vulnerability identified as CVE-2016-10163 represents a critical memory management flaw within the virglrenderer library, specifically affecting versions prior to 0.6.0. This issue resides in the vrend_renderer_context_create_internal function located within the vrend_decode.c source file, demonstrating a classic memory leak pattern that can be exploited to consume excessive host system resources. The vulnerability manifests when local guest operating system users repeatedly create decode contexts, leading to progressive memory consumption that ultimately results in denial of service conditions on the host system. This type of vulnerability is particularly concerning in virtualized environments where guest operating systems may have limited isolation mechanisms, allowing malicious or compromised guests to impact host stability and resource availability.
The technical nature of this flaw stems from improper memory deallocation within the rendering context creation process. When the vrend_renderer_context_create_internal function is invoked repeatedly by guest users, it fails to properly release previously allocated memory resources, creating a memory leak that accumulates over time. This memory consumption pattern aligns with CWE-401, which specifically addresses improper release of memory after use, making this vulnerability a clear example of memory management failure in software components. The vulnerability operates at the virtualization layer, where guest operating systems interact with host graphics rendering capabilities through virglrenderer, which serves as a bridge between virtualized graphics contexts and physical hardware acceleration.
The operational impact of CVE-2016-10163 extends beyond simple resource exhaustion, as it can severely compromise system stability and availability in virtualized environments. Host systems running vulnerable versions of virglrenderer become increasingly susceptible to performance degradation and potential system crashes as memory consumption continues to grow unchecked. This vulnerability particularly affects virtualization platforms that utilize virglrenderer for graphics acceleration, including various QEMU and KVM implementations where guest operating systems might be compromised or maliciously configured to exploit this flaw. The denial of service condition created by this memory leak can persist until the host system is manually restarted, making it a persistent threat to system uptime and reliability in production environments.
Mitigation strategies for this vulnerability require immediate patching of affected virglrenderer installations to version 0.6.0 or later, where the memory leak has been addressed through proper memory management practices. System administrators should implement monitoring solutions to detect unusual memory consumption patterns that might indicate exploitation attempts, particularly in environments with multiple virtual machines sharing host resources. Additionally, implementing resource limits and quotas for virtual machines can help contain the impact of such exploits by preventing any single guest from consuming excessive host memory resources. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving resource exhaustion and privilege escalation, as local guest users can leverage this flaw to indirectly compromise host system stability and availability. The remediation process should also include comprehensive testing of patched environments to ensure that the memory management improvements have been properly implemented and do not introduce new compatibility issues with existing virtualization workflows.