The Arm Mali GPU kernel driver allows unprivileged users to access freed memory because GPU memory operations are mishandled. This affects Bifrost r0p0 through r38p1, and r39p0; Valhall r19p0 through r38p1, and r39p0; and Midgard r4p0 through r32p0.
https://developer.arm.com/support/arm-security-updates
https://developer.arm.com/Arm%20Security%20Center/Mali%20GPU%20Driver%20Vulnerabilities
http://packetstormsecurity.com/files/172854/Android-Arm-Mali-GPU-Arbitrary-Code-Execution.html