Repo to clone for a so with a null returning malloc
To compile :
make
(rules : clean, fclean, all, re, libmalloc.so)
If you are on a normal shell : LD_PRELOAD=PATH/TO/SO
If you are on fish : setenv LD_PRELOAD PATH/TO/SO
If above did not work : export LD_PRELOAD=PATH/TO/SO
example : export LD_PRELOAD=$PWD/libmalloc.so
then launch commands and check how they fail to get any memory :)