bug#42530: 28.0.50; Integer overflows in alloc.c on macOS

[Lars Ingebrigtsen]

Philipp <p.stephani2@gmail.com> writes:

> -fsanitize=undefined finds the following integer overflows in alloc.c:
>
> alloc.c:4641:33: runtime error: addition of unsigned offset to 0x000102496c05 
> overflowed to 0x000102496c00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior alloc.c:4641:33 in 
> alloc.c:4852:9: runtime error: pointer index expression with base 
> 0xffffffffffffffff overflowed to 0x00010344053f
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior alloc.c:4852:9 in 

How do you reproduce this?  I tried

./configure CFLAGS='-g3 -O1 -fsanitize=address -fsanitize=undefined 
-fno-omit-frame-pointer' --with-modules --without-xml2 --without-pop 
--with-mailutils --enable-gcc-warnings=warn-only --enable-checking=all 
--enable-check-lisp-object-type 

and then started Emacs (on Catalina), but didn't get any errors as far
as I can see.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no