Yes, this is a compiler bug.

Footnote 84 of the C99 standard clearly says so: "Among the invalid
values for dereferencing a pointer by the unary * operator are a null
pointer, an address inappropriately aligned for the type of object
pointed to, and the address of an object after the end of its lifetime."
Before that sentence, only one exception is mentioned: (&*E == E) is
true, even in the case of a null pointer. IMHO the compiler can legally
do just about anything in the case of dereferencing a null pointer. The
lowest addressable object in C lives at address 1*sizeof(object). If null
was allowed as a valid pointer, there would be no pointer value to check
for invalid pointers. Sadly, this means that at least one byte (in the C
sense: a byte is a char) of the address space cannot be legally addressed
in C. If you consider this a bug, it's a language bug, but not a compiler
bug.