CVE-2017-6317 in virglrenderer
Summary
by MITRE
Memory leak in the add_shader_program function in vrend_renderer.c in virglrenderer before 0.6.0 allows local guest OS users to cause a denial of service (host memory consumption) via vectors involving the sprog variable.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability identified as CVE-2017-6317 represents a critical memory management flaw within the virglrenderer library, specifically affecting versions prior to 0.6.0. This issue manifests in the add_shader_program function located within the vrend_renderer.c source file, where improper memory handling creates conditions that can be exploited by local guest operating system users to execute denial of service attacks against the host system. The vulnerability operates through a memory leak mechanism that directly impacts host system resources, making it particularly dangerous in virtualized environments where guest systems share host resources.
The technical implementation of this vulnerability stems from inadequate memory deallocation within the shader program addition process. When the sprog variable is manipulated during shader program operations, the function fails to properly release previously allocated memory resources, leading to progressive memory consumption within the host system. This memory leak occurs repeatedly with each shader program addition attempt, creating a cumulative effect that can eventually exhaust available host memory resources. The flaw demonstrates characteristics consistent with CWE-401, which specifically addresses improper resource management and memory leaks in software systems. The vulnerability is particularly concerning because it operates at the virtualization layer, where guest operating systems have direct access to virtualized graphics resources through the virglrenderer component.
The operational impact of CVE-2017-6317 extends beyond simple resource exhaustion, creating potential for system instability and complete service disruption in virtualized environments. Local guest users can exploit this vulnerability without requiring elevated privileges, making it particularly dangerous in multi-tenant virtualization scenarios where multiple users share the same host infrastructure. The memory consumption pattern typically follows a predictable trajectory where each malicious shader program addition consumes additional host memory, potentially leading to system crashes or performance degradation that affects all virtual machines running on the compromised host. This vulnerability directly maps to ATT&CK technique T1499.001, which involves resource exhaustion attacks, and represents a classic example of how virtualization layer vulnerabilities can be leveraged for system-wide impact.
Mitigation strategies for CVE-2017-6317 primarily focus on upgrading to virglrenderer version 0.6.0 or later, where the memory leak has been resolved through proper memory management practices. System administrators should implement regular patch management protocols to ensure all virtualization components remain current with security updates. Additionally, monitoring for unusual memory consumption patterns in virtualized environments can help detect exploitation attempts before they cause significant disruption. Network segmentation and access controls should be implemented to limit guest user privileges where possible, reducing the attack surface for local exploitation. The vulnerability highlights the importance of thorough memory management testing in virtualization components and demonstrates how seemingly isolated issues in graphics rendering libraries can have cascading effects on entire host system stability. Organizations should also consider implementing automated monitoring solutions that can detect abnormal memory usage patterns indicative of memory leak exploitation attempts.