Google Pixel MFC H264 Processing Memory Corruption

There is a memory corruption issue in the MFC media processing core on the Pixel 7. It occurs when decoding a malformed H264 stream in Chrome, likely to due to an out of bounds quantization parameter. A write to plane 0 that occurs during macroblock decoding extends past the allocated bounds of the plane, and can overwrite the motion vector (MV) buffer or cause a crash if the adjacent address is unmapped. Both of these allocations are DMA buffers and it is unclear whether this condition is exploitable.