malloc error when trying to assign the returned pointer to a struct field

[rempas]

On Saturday, 9 September 2023 at 09:56:59 UTC, H. S. Teoh wrote:
> libc doesn't know what you intended. All it knows is that you 
> asked it for 20 bytes (even though you actually needed 40), 
> then later on its internal structures are corrupted (because 
> you thought you got 40 bytes; storing data past the 20 bytes 
> overwrote some of malloc's internal data -- this is the buffer 
> overrun / buffer overflow I referred to). So it aborts the 
> program instead of continuing to run in a compromised state.
>
>
> T

Thank you! I fully realize now what's the problem! And that was 
indeed a very sneaky problem. The good news is that I'm mostly 
done with these memory structures and functions so I will 
probably take a while since I find something similar.

I'm lucky there are people smarter, more experience that are 
willing to help. Bless you all and have a great day!