If you overwrite more memory than you allocated, you crash, or
corrupt memory, or open yourself to a security hole. (a/k/a "buffer
overflow")
char *p = malloc( 10 ); strcpy( p, "Hello, world!" );
or
char *p = malloc(10); p[10] = 'x'; /* Off-by-one, a fencepost error */TOC | Prev | Next