CVE-2023-4295: Arm Mali GPU Kernel Use-After-Free Flaw

CVE-2023-4295 Overview

CVE-2023-4295 is a Use-After-Free vulnerability affecting Arm Mali GPU kernel drivers. A local non-privileged user can make improper GPU memory processing operations to gain access to already freed memory. This vulnerability stems from an integer overflow weakness (CWE-190) that leads to a use-after-free condition, potentially allowing attackers to achieve local privilege escalation on affected systems.

Critical Impact

Local attackers with low privileges can exploit improper GPU memory operations to access freed memory, potentially leading to code execution with elevated privileges or system compromise on devices using affected Arm Mali GPU drivers.

Affected Products

• Arm Mali GPU Kernel Driver
• Arm Valhall GPU Kernel Driver

Discovery Timeline

• 2023-11-07 - CVE-2023-4295 published to NVD
• 2025-03-24 - Last updated in NVD database

Technical Details for CVE-2023-4295

Vulnerability Analysis

This vulnerability resides in the Arm Mali GPU kernel driver's memory management subsystem. The core issue involves improper handling of GPU memory processing operations that allows a local non-privileged user to manipulate memory in a way that results in accessing already freed memory regions. The vulnerability is classified under CWE-190 (Integer Overflow or Wraparound), indicating that an integer overflow condition triggers the subsequent use-after-free scenario.

The attack requires local access to the system and low privileges, but does not require user interaction. Successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected system, as the attacker may gain the ability to execute arbitrary code in kernel context.

Root Cause

The vulnerability originates from an integer overflow condition in the GPU memory processing logic. When specific memory operations are performed, an integer value used in size calculations or index computations can overflow, leading to incorrect memory allocation or deallocation. This arithmetic error subsequently results in a use-after-free condition where the driver continues to reference memory that has already been released back to the memory pool.

Attack Vector

The attack is conducted locally by a non-privileged user who has access to the GPU driver interface. The attacker crafts specific GPU memory operations that trigger the integer overflow condition. Once the overflow occurs, it corrupts the memory management state, causing the driver to access memory that has been freed. By carefully controlling the timing and content of memory allocations, an attacker can potentially place controlled data in the freed memory region, leading to arbitrary code execution when the dangling pointer is dereferenced.

The exploitation flow involves:

1. Triggering specific GPU memory allocation patterns
2. Causing an integer overflow in size calculations
3. Inducing premature memory deallocation
4. Causing the driver to access the freed memory region
5. Potentially achieving code execution with kernel privileges

Technical details regarding the overflow and use-after-free mechanism are available in the Packet Storm Security advisory.

Detection Methods for CVE-2023-4295

Indicators of Compromise

• Unusual kernel crashes or GPU driver errors indicating memory corruption
• Unexpected privilege escalation attempts from low-privileged processes accessing GPU interfaces
• Anomalous memory allocation patterns in GPU driver logs
• System instability following GPU-intensive operations from non-privileged user accounts

Detection Strategies

• Monitor kernel logs for Mali GPU driver crashes or memory-related errors
• Implement kernel address space layout randomization (KASLR) to make exploitation more difficult
• Deploy runtime memory corruption detection tools that can identify use-after-free conditions
• Monitor for unusual system calls or ioctl operations to GPU device files from unprivileged processes

Monitoring Recommendations

• Enable comprehensive kernel logging for GPU driver operations
• Implement system call auditing for processes accessing /dev/mali* device files
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation attempts
• Monitor for privilege escalation patterns following GPU driver interactions

How to Mitigate CVE-2023-4295

Immediate Actions Required

• Update affected Arm Mali GPU kernel drivers to the latest patched version immediately
• Review and restrict access to GPU device files for non-essential users where possible
• Implement additional kernel hardening measures such as KASLR and stack canaries
• Monitor systems for signs of exploitation attempts while patches are being deployed

Patch Information

Arm has released security updates to address this vulnerability. Administrators should consult the Arm Security Center Mali GPU Driver Vulnerabilities page for detailed patch information and updated driver versions. Organizations should prioritize deployment of these patches, particularly on multi-user systems or devices where local privilege escalation poses a significant risk.

Workarounds

• Restrict access to GPU device nodes (/dev/mali*) to only trusted users and applications
• Implement mandatory access control (MAC) policies using SELinux or AppArmor to limit GPU driver access
• Consider disabling GPU acceleration for untrusted applications where feasible
• Apply principle of least privilege to all user accounts on affected systems

# Example: Restrict access to Mali GPU device files
chmod 660 /dev/mali*
chown root:gpu /dev/mali*
# Only users in the 'gpu' group will have access to the GPU device