@alanc @solardiz I guess as Ulrich Drepper pointed you'd need to check the return value before using *ptr, which makes a bit of sense to me although it's a footgun for asprintf to not make *ptr NULL in case of error.
At least I think it's doable for static analyzers to require error checking for asprintf and I guess if it gets into ISO C with the same problem, for compilers to do the check.