The article says two different things about how free() works: 1. In case of NULL pointer free does no action. 2. In "double free corruption" section, it sa

The article says two different things about how free() works: 1. In case of NULL pointer free does no action. 2. In "double free corruption" section, it says "Could be caused by calling free with pointer, which is [..] NULL pointer" So: which is it? Otherwise, there's no point in the NULL/assert() dance, you can freely free() with impunity: struct foo *a, *b, *c; a=NULL; b=NULL; c=NULL; a=malloc(sizeof *a); b=malloc(sizeof *b); c=malloc(sizeof *c); if(!(a && b && c)) {free(a); free(b); free(c); return 1;}