Question to understand texture share

I am currently looking at a project of mine (webbrowser support in Kodi), where it would be necessary to exchange textures between different processes (Chromium Sandbox system).

Unfortunately, I still lack OpenGL experience with sharing between apps and cannot find out exactly how the following problem comes about and can be solved.

In your example only 4 pixels are exchanged so that this thing is not visible. Unfortunately, when a larger structure is exchanged, it does not arrive correctly at the client.

Here's how it's represented:

My test code of it is here https://github.com/AlwinEsch/dma-buf-texture-sharing/tree/own-tries where it takes a stored texture file for test.

Any idea what the cause is and how to fix it?

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My Hardware:

• OS: Ubuntu 20.04
• CPU: Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz
• GPU: Intel Corporation UHD Graphics 630 (Desktop 9 Series)