Tencent ncnn Conversion API mat_pixel.cpp yuv420sp2rgb integer overflow

A security flaw has been discovered in Tencent ncnn up to 44b02dabdcf97499281a4692ebd65bad73dcf8b6. Affected by this issue is the function ncnn::yuv420sp2rgb of the file src/mat_pixel.cpp of the component Conversion API. The manipulation results in integer overflow. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.