CVE-2017-5577 in Linux
Summary
by MITRE
The vc4_get_bcl function in drivers/gpu/drm/vc4/vc4_gem.c in the VideoCore DRM driver in the Linux kernel before 4.9.7 does not set an errno value upon certain overflow detections, which allows local users to cause a denial of service (incorrect pointer dereference and OOPS) via inconsistent size values in a VC4_SUBMIT_CL ioctl call.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2017-5577 resides within the VideoCore DRM driver component of the Linux kernel, specifically affecting versions prior to 4.9.7. This issue manifests in the vc4_get_bcl function located in drivers/gpu/drm/vc4/vc4_gem.c, where the function fails to properly handle error conditions during overflow detection scenarios. The root cause stems from the absence of appropriate errno value setting when certain overflow conditions are detected, creating a critical gap in the kernel's error handling mechanisms. This flaw operates within the broader context of GPU driver security within the Linux operating system, where proper error propagation is essential for maintaining system stability and preventing unauthorized access patterns.
The technical implementation of this vulnerability involves the VC4_SUBMIT_CL ioctl call which serves as the interface for submitting command lists to the VideoCore GPU. When inconsistent size values are provided during this ioctl operation, the vc4_get_bcl function encounters overflow conditions that should trigger appropriate error responses. However, due to the missing errno assignment, the function continues execution with invalid parameters, leading to incorrect pointer dereference operations. This failure mode results in kernel OOPS messages and ultimately causes a system crash or denial of service condition that affects the entire graphics subsystem. The vulnerability represents a classic case of improper error handling where the system fails to properly validate input parameters and respond with appropriate error codes.
From an operational impact perspective, this vulnerability enables local users to exploit the kernel's GPU driver functionality to cause system-wide denial of service conditions. The attack vector requires local system access and involves crafting specific ioctl calls with malformed size parameters, making it particularly concerning for systems where untrusted users might have access to GPU resources. The resulting system instability can affect graphics rendering, video playback, and overall system performance, potentially disrupting critical applications that depend on GPU acceleration. This vulnerability aligns with CWE-252, which addresses "Unchecked Return Value" conditions in software development, where the failure to properly handle return values leads to unexpected system states. The impact extends beyond simple service disruption to potentially compromise the integrity of GPU-based operations and the overall kernel stability.
The mitigation strategies for CVE-2017-5577 primarily involve upgrading to Linux kernel versions 4.9.7 or later, where the proper error handling has been implemented to address the missing errno assignments. System administrators should prioritize kernel updates, particularly in environments where multiple users have local access to systems with GPU capabilities. Additional protective measures include implementing proper access controls to limit local user privileges, monitoring for suspicious ioctl activity patterns, and maintaining regular security audits of kernel components. The vulnerability demonstrates the importance of comprehensive error handling in kernel space code and aligns with ATT&CK technique T1489, which covers "Service Stop" and related denial of service attacks that can be executed through kernel-level vulnerabilities. Organizations should also consider implementing kernel hardening measures and ensuring that all GPU-related drivers are kept current with security patches to prevent exploitation of similar issues in other kernel components.