CVE-2021-1056: Nvidia GPU Driver DOS Vulnerability

CVE-2021-1056 Overview

CVE-2021-1056 is a vulnerability in the NVIDIA GPU Display Driver for Linux that affects the kernel mode layer (nvidia.ko). The driver fails to completely honor operating system file system permissions, which compromises GPU device-level isolation. This improper permission handling can allow a local attacker with low privileges to gain unauthorized access to GPU resources, potentially leading to information disclosure or denial of service conditions.

Critical Impact

Local attackers can bypass file system permissions to access GPU resources belonging to other users, enabling information disclosure of sensitive GPU memory contents or denial of service by disrupting GPU operations for other processes.

Affected Products

• NVIDIA GPU Driver (all versions prior to the patched release)
• Linux Kernel (when using affected NVIDIA drivers)
• Debian Linux 9.0 (Stretch)

Discovery Timeline

• 2021-01-08 - CVE-2021-1056 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-1056

Vulnerability Analysis

This vulnerability stems from an improper default permissions issue (CWE-276) in the NVIDIA GPU Display Driver's kernel mode layer. The nvidia.ko kernel module does not fully enforce operating system file system permissions when managing GPU device access, which undermines the intended isolation between different users and processes accessing the GPU.

In multi-user or containerized environments, proper GPU device isolation is critical for security. When the driver fails to honor these permissions correctly, a local user with legitimate but limited access to the system can potentially access GPU memory or resources allocated to other users or processes. This could expose sensitive data processed by the GPU, such as machine learning model weights, rendered graphics buffers, or cryptographic operations performed on the GPU.

The local attack vector requires an authenticated user to already have access to the system, but the exploitation does not require any user interaction, making it particularly concerning in shared computing environments like research clusters, cloud GPU instances, or multi-user workstations.

Root Cause

The root cause is an improper default permissions vulnerability (CWE-276) within the NVIDIA kernel module (nvidia.ko). The module fails to properly validate and enforce file system permission checks when granting access to GPU device resources. This allows processes to access GPU resources that should be restricted based on standard Linux permission models, effectively bypassing the operating system's access control mechanisms for GPU device isolation.

Attack Vector

The attack requires local access to the affected system. An attacker with a low-privileged user account can exploit this vulnerability without requiring any user interaction. The attack targets the GPU device isolation mechanisms, allowing the attacker to either:

1. Information Disclosure: Access GPU memory contents belonging to other users or processes, potentially exposing sensitive computation data, model parameters, or rendered content.

2. Denial of Service: Disrupt GPU operations for other processes by interfering with GPU resource allocation or causing GPU errors that affect system stability.

The vulnerability is particularly impactful in shared GPU computing environments where multiple users or containers share access to GPU resources.

Detection Methods for CVE-2021-1056

Indicators of Compromise

• Unexpected GPU memory access patterns or allocation requests from low-privileged processes
• Anomalous read operations targeting GPU device files outside of expected process contexts
• Unusual access to /dev/nvidia* device files by processes without legitimate GPU workloads
• GPU resource contention or errors that cannot be attributed to known workloads

Detection Strategies

• Monitor system logs for unusual GPU driver errors or permission-related messages from the nvidia.ko module
• Implement file integrity monitoring on NVIDIA driver kernel modules to detect unauthorized modifications
• Deploy endpoint detection capabilities to identify processes exhibiting abnormal GPU access patterns
• Audit user access to GPU device files and compare against expected application behavior

Monitoring Recommendations

• Enable verbose logging for the NVIDIA driver where possible to capture detailed access information
• Implement monitoring for GPU memory utilization anomalies that could indicate unauthorized access
• Use SentinelOne's behavioral AI to detect processes exhibiting suspicious GPU resource access patterns
• Establish baselines for normal GPU usage patterns to identify deviations that may indicate exploitation

How to Mitigate CVE-2021-1056

Immediate Actions Required

• Update NVIDIA GPU drivers to the latest patched version as specified in the NVIDIA Support Article
• Review and restrict access to GPU device files (/dev/nvidia*) to only authorized users and processes
• Implement process isolation for GPU workloads using containers or separate user accounts with strict permissions
• Audit current GPU access permissions and remove unnecessary access grants

Patch Information

NVIDIA has released updated drivers that address this vulnerability. Administrators should consult the NVIDIA Security Bulletin for specific patched driver versions applicable to their GPU hardware. For Debian-based systems, refer to the Debian LTS Announcement for package update information. Gentoo users should review GLSA 202310-02 for guidance.

Workarounds

• Restrict physical and logical access to systems with NVIDIA GPUs to trusted users only
• Use Linux security modules (SELinux, AppArmor) to implement mandatory access controls on GPU device files
• Isolate sensitive GPU workloads on dedicated systems without shared user access
• Consider disabling GPU sharing in multi-user environments until patches can be applied

# Restrict GPU device file permissions as a temporary mitigation
# Review current permissions
ls -la /dev/nvidia*

# Restrict access to GPU devices to specific group
sudo chown root:gpu /dev/nvidia*
sudo chmod 660 /dev/nvidia*

# Add only authorized users to the gpu group
sudo usermod -aG gpu authorized_user