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bd7185bad1
When compiled -fsanitize=undefined nasm produced this error message:
asm/preproc.c:2523:25: runtime error: member access within null pointer of type 'struct Token'
The problem is reproducible on tests avx512f, avx512cd, avx512pf
and avx512er in the test suite.
The problematic line was:
/* Advance to the next comma */
maybe_comma = &t->next; <<< HERE
while (tok_isnt(t, ',')) {
if (!tok_white(t))
comma = NULL; /* Non-empty parameter */
maybe_comma = &t->next;
t = t->next;
}
When t is NULL this line doesn't cause memory access, but it is still an
undefined behavior according to C standard.
I believe that the underlying problem is that this loop doesn't have a sound
invariant about maybe_comma:
* On first iteration: *maybe_comma == t->next
* On the following iterations: *maybe_comma == t
I don't know what the intended loop invariant is and I decided to just
mechanically fix the deferencing of NULL pointer, completely preserving
the existing behavior.
Signed-off-by: Ivan Sorokin <vanyacpp@gmail.com>