CVE-2023-32804: Arm 5th Gen GPU Driver Buffer Overflow Flaw

CVE-2023-32804 Overview

CVE-2023-32804 is an out-of-bounds write vulnerability affecting multiple Arm Mali GPU userspace drivers, including Midgard, Bifrost, Valhall, and Arm 5th Gen GPU Architecture drivers. This vulnerability allows a local non-privileged user to write a constant pattern to a limited amount of memory not allocated by the userspace driver, potentially leading to privilege escalation, data corruption, or system instability.

Critical Impact

Local attackers with non-privileged access can exploit this out-of-bounds write vulnerability to corrupt memory outside allocated boundaries, potentially achieving code execution or escalating privileges on affected mobile devices and embedded systems using Arm Mali GPUs.

Affected Products

• Arm Midgard GPU Userspace Driver (versions r0p0 through r32p0)
• Arm Bifrost GPU Userspace Driver (versions r0p0 through r44p0)
• Arm Valhall GPU Userspace Driver (versions r19p0 through r44p0)
• Arm 5th Gen GPU Architecture Userspace Driver (versions r41p0 through r44p0)

Discovery Timeline

• 2023-12-04 - CVE-2023-32804 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-32804

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption flaw that occurs when a program writes data past the end or before the beginning of the intended buffer. In the context of Arm Mali GPU userspace drivers, the vulnerability allows an attacker to write a constant pattern to memory regions that were not allocated by the driver.

The impact is significant for mobile devices and embedded systems that utilize Arm Mali GPUs, which are prevalent in Android smartphones, tablets, Chromebooks, and various IoT devices. Successful exploitation requires local access with low privileges and no user interaction, making it particularly dangerous in multi-user environments or on compromised devices where an attacker has gained initial foothold.

Root Cause

The root cause of CVE-2023-32804 lies in improper boundary validation within the GPU userspace driver's memory handling routines. The driver fails to properly validate memory write operations, allowing writes to extend beyond the boundaries of allocated memory regions. This insufficient bounds checking permits a local user to write a predictable constant pattern to memory areas that should be protected from unauthorized access.

The vulnerability spans multiple generations of Arm Mali GPU architectures, indicating a fundamental flaw in the shared codebase or common memory management logic used across these driver families.

Attack Vector

The attack vector is local, requiring the attacker to have code execution capability on the target system. The exploitation scenario involves a malicious application or process invoking GPU driver functions with crafted parameters that trigger the out-of-bounds write condition.

An attacker could exploit this vulnerability by:

1. Crafting malicious GPU memory allocation or mapping requests
2. Triggering driver operations that write constant patterns
3. Directing these writes to memory regions outside the allocated boundaries
4. Potentially corrupting kernel data structures, achieving privilege escalation, or causing system instability

The limited nature of the write (constant pattern to limited memory) may constrain full exploitation, but strategic targeting of specific memory regions could still enable meaningful attacks such as overwriting security-critical flags or function pointers.

Detection Methods for CVE-2023-32804

Indicators of Compromise

• Unexpected system crashes or kernel panics related to GPU driver operations
• Anomalous memory access patterns or corruption detected in system logs
• Unusual GPU driver behavior or error messages indicating memory boundary violations
• Applications making suspicious GPU-related system calls

Detection Strategies

• Monitor for unusual patterns in GPU driver API calls from unprivileged processes
• Implement kernel-level memory integrity monitoring to detect unauthorized writes
• Deploy endpoint detection solutions capable of identifying memory corruption attempts
• Analyze system crash dumps for evidence of out-of-bounds write exploitation attempts

Monitoring Recommendations

• Enable detailed logging for GPU driver operations where supported
• Configure crash reporting to capture kernel panic details for analysis
• Implement application allowlisting on sensitive systems to prevent unauthorized code execution
• Deploy SentinelOne agents to monitor for suspicious process behavior targeting GPU drivers

How to Mitigate CVE-2023-32804

Immediate Actions Required

• Update Arm Mali GPU drivers to patched versions beyond the affected ranges (later than r32p0 for Midgard, r44p0 for Bifrost, Valhall, and 5th Gen)
• Contact device manufacturers or OEMs for firmware updates addressing this vulnerability
• Limit installation of untrusted applications on affected devices
• Implement application sandboxing to contain potential exploitation attempts

Patch Information

Arm has released updated driver versions to address this vulnerability. Organizations should consult the Arm Security Center Mali GPU Driver Vulnerabilities page for official patch information and driver updates.

For mobile devices, patches are typically distributed through Android security bulletins and device manufacturer firmware updates. Users should ensure their devices are running the latest available security patches.

Workarounds

• Restrict the installation of applications from untrusted sources
• Implement strict application permission policies to limit GPU access
• Use mobile device management (MDM) solutions to enforce security policies on enterprise devices
• Consider disabling GPU acceleration for high-security use cases until patches are applied (may impact performance)