Use After Free vulnerability in Arm Ltd Midgard GPU Kernel Driver, Arm Ltd Bifrost GPU Kernel Driver, Arm Ltd Valhall GPU Kernel Driver, Arm Ltd Arm 5th Gen GPU Architecture Kernel Driver allows a local non-privileged user to make improper GPU memory processing operations to gain access to already freed memory.This issue affects Midgard GPU Kernel Driver: from r19p0 through r32p0; Bifrost GPU Kernel Driver: from r7p0 through r48p0; Valhall GPU Kernel Driver: from r19p0 through r48p0; Arm 5th Gen GPU Architecture Kernel Driver: from r41p0 through r48p0.
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:
In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.