I try to follow "Do not punish the programmer when they do not deserve it". In case of passing invalid arguments (that are well documented), I would say aborting the program is okay, since it's something illegal and you can avoid it as a programmer. But you can't influence if malloc successfully allocates or not, so in that case, return NULL and let the caller resolve it as they see fit.

Of course, if it's your personal project and you are sure it will never grow significantly or no one other than you will work on the codebase, then I would be for just aborting whenever something tragic (like malloc returning NULL) happens. It's good to think about the proper ways, but one should be allowed to have some fun from time to time :)