Re: Linux 6.2-rc1

[Kees Cook]

On December 26, 2022 4:29:41 PM PST, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>On Mon, Dec 26, 2022 at 01:03:59PM -0800, Kees Cook wrote:
>> On December 26, 2022 12:56:29 PM PST, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>> >On Mon, Dec 26, 2022 at 11:52 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>> >>
>> >> fs/f2fs/inline.c: In function 'f2fs_move_inline_dirents':
>> >> include/linux/fortify-string.h:59:33: error: '__builtin_memset' pointer overflow between offset [28, 898293814] and size [-898293787, -1] [-Werror=array-bounds]
>> >> fs/f2fs/inline.c:430:9: note: in expansion of macro 'memset'
>> >>   430 |         memset(dst.bitmap + src.nr_bitmap, 0, dst.nr_bitmap - src.nr_bitmap);
>> >>       |         ^~~~~~
>> >
>> >Well, that's unfortunate.
>> 
>> I'll look into this.
>> 
>
>I did some more testing. The problem is seen with gcc 11.3.0, but not with
>gcc 12.2.0 nor with gcc 10.3.0.

That's what I'd expect: 10 didn't have variable range tracking wired up to -Warray-bounds, 11 does, and we disable -Warray-bounds on 12 because of 3 separate 12-only GCC bugs.

> gcc bug ? Should I switch to gcc 12.2.0 for
>powerpc when build testing the latest kernel ?

Sure? But that'll just hide it. I suspect GCC has found a way for dst.nr_bitmap to be compile-time 27, so the size is always negative.


-- 
Kees Cook