CVE-2017-5994 in virglrenderer
Summary
by MITRE
Heap-based buffer overflow in the vrend_create_vertex_elements_state function in vrend_renderer.c in virglrenderer before 0.6.0 allows local guest OS users to cause a denial of service (out-of-bounds array access and crash) via the num_elements parameter.
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Analysis
by VulDB Data Team • 09/08/2020
The vulnerability identified as CVE-2017-5994 represents a critical heap-based buffer overflow flaw within the virglrenderer library, specifically affecting the vrend_create_vertex_elements_state function in vrend_renderer.c. This issue exists in versions prior to 0.6.0 and creates a significant security risk for virtualized environments where guest operating systems interact with the virtual graphics hardware. The vulnerability is particularly concerning as it enables local privilege escalation within guest OS contexts, allowing malicious actors to exploit the buffer overflow condition to disrupt system operations.
The technical flaw manifests through improper validation of the num_elements parameter within the vertex elements state creation process. When a guest OS attempts to create vertex elements with an excessive number of elements, the function fails to properly bounds-check the input value against the allocated heap memory buffer. This oversight results in out-of-bounds array access patterns that corrupt adjacent memory regions, ultimately leading to application crashes and system instability. The heap-based nature of the vulnerability means that the memory corruption occurs in the heap allocation space rather than on the stack, making it particularly challenging to detect and exploit reliably.
From an operational impact perspective, this vulnerability creates substantial risks for virtualization environments where multiple guest operating systems share the same host resources. The denial of service condition can be triggered by any local user within a guest OS, potentially allowing attackers to repeatedly crash virtual graphics drivers and render the virtualized graphics functionality unusable. This type of vulnerability directly impacts the availability and reliability of virtualized applications and services, making it particularly dangerous in enterprise environments where virtualization is extensively used for server consolidation and cloud computing deployments. The vulnerability can be exploited to cause persistent system instability that may require complete system restarts to resolve.
The security implications extend beyond simple denial of service to potentially enable more sophisticated attack vectors within virtualized environments. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter. The flaw can be leveraged to create persistent access points within virtualized systems, particularly when combined with other vulnerabilities in the graphics stack. Organizations utilizing virglrenderer for virtual graphics acceleration should prioritize immediate patching to prevent exploitation, as the vulnerability can be triggered through legitimate graphics API calls without requiring elevated privileges.
Mitigation strategies should include immediate deployment of virglrenderer version 0.6.0 or later, which contains the necessary patches to address the buffer overflow condition. System administrators should also implement monitoring for unusual graphics driver behavior and consider implementing additional virtualization security controls to limit guest OS capabilities. The vulnerability highlights the importance of proper input validation in graphics driver code and demonstrates the need for comprehensive security testing of virtualization components. Organizations should conduct thorough vulnerability assessments of their virtualized environments to identify other potential heap-based buffer overflow conditions that may exist in similar graphics libraries or virtualization components.