Re: Reporting Security Violations in Software Package

On 3/18/25 11:42, Kaz Kylheku wrote:
> in the case of Clang, we cannot look to its offsetof
> definition to hypothesize that it has a null pointer arithmetic
> extension.

Yes, and 'clang -fsanitize=undefined' reports a runtime error if you add 
0 to a null pointer. However, Gnulib is documented to rely on adding 0 
to a null pointer, and our response has consistently been "Don't use 
Clang that way".

This is not the only place that Gnulib doesn't strictly conform to C, 
and it's not an area that we should need to worry about. Once C2y comes 
out and says it's OK to add 0 to a null pointer, the clang 
-fsanitize=undefined issue should go away. In the meantime, one should 
not use clang -fsanitize=undefined in production code (there are other 
good reasons for this).

Luckily, 'gcc -fsanitize=undefined' doesn't have the problem.