[Rpm-maint] [rpm-software-management/rpm] Undefined pointer comparison in macro.c (#1602)

[Demi Marie Obenour]

> That is probably undefined behavior in C11 but AIUI not in C99, which rpm uses.

It is undefined in C99; see http://www.open-std.org/jtc1/sc22/wg14/www/C99RationaleV5.10.pdf, §6.3.2.3:

> Regardless how an invalid pointer is created, any use of it yields undefined behavior.

So I still believe it should be fixed.

> Perhaps I wasn't clear enough in my earlier comment today: as a rule of thumb, I'm _not_ interested in undefined behavior findings, exactly because of it's totally undefined what standard it's checking. Unless it reveals a concrete bug of course.

This is undefined behavior in C99, and includes a reproducible test case.  I consider that to be a concrete bug.


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