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SubjectRe: [PATCH 1/2] kasan: test: use underlying string helpers
On Thu, 14 Oct 2021 19:40:45 -0700 Kees Cook <keescook@chromium.org> wrote:

>
>
> On October 14, 2021 1:12:54 AM PDT, Vincenzo Frascino <vincenzo.frascino@arm.com> wrote:
> >
> >
> >On 10/13/21 5:00 PM, Arnd Bergmann wrote:
> >> From: Arnd Bergmann <arnd@arndb.de>
> >>
> >> Calling memcmp() and memchr() with an intentional buffer overflow
> >> is now caught at compile time:
> >>
> >> In function 'memcmp',
> >> inlined from 'kasan_memcmp' at lib/test_kasan.c:897:2:
> >> include/linux/fortify-string.h:263:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter)
> >> 263 | __read_overflow();
> >> | ^~~~~~~~~~~~~~~~~
> >> In function 'memchr',
> >> inlined from 'kasan_memchr' at lib/test_kasan.c:872:2:
> >> include/linux/fortify-string.h:277:17: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter)
> >> 277 | __read_overflow();
> >> | ^~~~~~~~~~~~~~~~~
> >>
> >> Change the kasan tests to wrap those inside of a noinline function
> >> to prevent the compiler from noticing the bug and let kasan find
> >> it at runtime.
> >>
> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >
> >Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>
> How about just explicitly making the size invisible to the compiler?
>
> I did this for similar issues in the same source:
>
> https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u
>

Arnd?

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