CVE-2023-34970: Arm Mali GPU Driver Race Condition Flaw

CVE-2023-34970 Overview

A vulnerability exists in the Arm Mali GPU Kernel Driver that allows a local non-privileged user to make improper GPU processing operations. This flaw can be exploited to access a limited amount of memory outside of buffer bounds or to exploit a software race condition. If an attacker carefully prepares the system's memory, they can potentially gain access to already freed memory, leading to a use-after-free condition.

Critical Impact

Local attackers can exploit improper GPU processing operations to trigger out-of-bounds memory access or race conditions, potentially leading to denial of service through use-after-free vulnerabilities.

Affected Products

• Arm Mali GPU Kernel Driver version r44p0
• Arm Valhall GPU Kernel Driver version r44p0

Discovery Timeline

• 2023-10-03 - CVE CVE-2023-34970 published to NVD
• 2025-03-07 - Last updated in NVD database

Technical Details for CVE-2023-34970

Vulnerability Analysis

This vulnerability combines two distinct memory safety issues within the Arm Mali GPU Kernel Driver: an out-of-bounds memory access (CWE-787) and a use-after-free condition (CWE-416). The flaw resides in how the driver processes GPU operations, where insufficient boundary validation allows memory access beyond allocated buffer limits.

The race condition component introduces a time-of-check time-of-use (TOCTOU) scenario where a local attacker can manipulate memory state between validation and use. By carefully timing their operations and preparing system memory, an attacker can force the driver to reference memory that has already been deallocated, creating a classic use-after-free situation.

The attack requires local access and low privileges, but exploitation complexity is considered high due to the need for precise timing and memory manipulation. Successful exploitation primarily affects system availability, potentially causing system crashes or denial of service conditions.

Root Cause

The root cause stems from inadequate bounds checking in GPU processing operations combined with improper synchronization of memory operations. The driver fails to properly validate memory boundaries before accessing GPU buffers, and a race condition in the memory management logic allows freed memory to be accessed if an attacker can win the race between memory deallocation and subsequent use.

Attack Vector

The attack requires local access to the system with low-level user privileges. An attacker must be able to interact with the Mali GPU driver through standard GPU processing interfaces. The exploitation process involves:

1. A local non-privileged user initiates GPU processing operations
2. The attacker manipulates memory allocation and deallocation timing
3. By exploiting the race condition, the attacker causes the driver to access memory outside buffer bounds
4. Carefully prepared memory layouts enable access to freed memory regions
5. The resulting use-after-free can lead to system instability or denial of service

The vulnerability manifests in the GPU processing operations where boundary validation is insufficient. Attackers can trigger out-of-bounds access by crafting malicious GPU operations that exceed expected buffer limits. The race condition can be exploited by rapidly allocating and freeing memory while GPU operations are in progress. For detailed technical information, see the ARM Security Center Mali GPU Driver Vulnerabilities advisory.

Detection Methods for CVE-2023-34970

Indicators of Compromise

• Unexpected system crashes or kernel panics related to Mali GPU driver operations
• Abnormal GPU memory allocation patterns or excessive GPU memory pressure
• Kernel log entries indicating out-of-bounds memory access in Mali driver modules
• Process crashes with memory corruption signatures when interacting with GPU resources

Detection Strategies

• Monitor kernel logs for Mali GPU driver errors, particularly memory access violations or use-after-free indicators
• Implement system call monitoring for unusual patterns of GPU-related operations from low-privileged processes
• Deploy memory corruption detection tools that can identify out-of-bounds access patterns
• Use kernel address sanitizer (KASAN) in development environments to detect memory safety violations

Monitoring Recommendations

• Enable verbose logging for the Mali GPU kernel driver to capture detailed operation traces
• Monitor system stability metrics, tracking unexpected GPU driver restarts or system crashes
• Implement alerting for kernel panic events associated with Mali driver modules
• Review process behavior for applications making excessive or unusual GPU memory operations

How to Mitigate CVE-2023-34970

Immediate Actions Required

• Update the Arm Mali GPU Kernel Driver to the latest patched version beyond r44p0
• Review and restrict access to GPU resources for untrusted users or processes
• Enable kernel hardening features such as KASLR and stack protectors
• Monitor affected systems for signs of exploitation attempts

Patch Information

Arm has released security updates addressing this vulnerability. System administrators and device manufacturers should obtain the latest Mali GPU Kernel Driver from Arm. Refer to the ARM Security Center Mali GPU Driver Vulnerabilities page for official patch information and updated driver versions.

For devices where the GPU driver is bundled with the operating system (such as Android devices), users should apply security updates from their device manufacturer or carrier that include the patched Mali driver.

Workarounds

• Restrict GPU access to trusted applications only where possible through system permission controls
• Implement additional access controls to limit which users can interact with GPU resources
• Consider sandboxing applications that require GPU access to limit potential impact
• Monitor and limit the rate of GPU memory operations from untrusted processes

If immediate patching is not possible, system administrators should implement defense-in-depth measures by restricting local user access and monitoring for unusual GPU-related activity. Contact your device manufacturer or Arm support for guidance on applying security updates to affected systems.