^{CVE-2021-29256:}Use-After-Free vulnerability in Arm Mali GPU kernel driver allows unprivileged users to access freed memory, potentially leading to information disclosure or root privilege escalation.

Overview

The vulnerability (CVE-2021-29256) is a use-after-free issue in the Arm Mali GPU kernel driver. When exploited, an unprivileged user can access memory that has been freed, which can lead to two potential security impacts: information disclosure or privilege escalation to root level. This is particularly concerning as it affects multiple generations of Arm Mali GPUs across various versions:

• Bifrost: versions r16p0 through r29p0 (versions before r30p0)
• Valhall: versions r19p0 through r29p0 (versions before r30p0)
• Midgard: versions r28p0 through r30p0

The vulnerability allows attackers to potentially read sensitive information from freed memory or manipulate memory in a way that leads to privilege escalation, compromising the entire system security.

Remediation

To address this vulnerability, users should:

1. Update to patched versions of the Arm Mali GPU kernel driver:

   • For Bifrost: Update to r30p0 or later
   • For Valhall: Update to r30p0 or later
   • For Midgard: Update beyond r30p0 (check with vendor for specific patch version)

2. If immediate updates are not possible, consider implementing the following mitigations:

   • Restrict physical access to affected devices
   • Monitor system logs for unusual GPU-related activities
   • Implement strict access controls for users
   • Apply any interim patches provided by device manufacturers or system integrators

3. System administrators should coordinate with their hardware vendors or device manufacturers to ensure appropriate patches are applied as soon as they become available.

References

1. Arm Security Updates for Mali GPU Kernel Driver: https://developer.arm.com/support/arm-security-updates/mali-gpu-kernel-driver
2. Common Weakness Enumeration (CWE-416): Use After Free - https://cwe.mitre.org/data/definitions/416.html
3. MITRE CVE Entry: CVE-2021-29256