Messages in this thread | | | From | Arnd Bergmann <> | Date | Mon, 18 Oct 2021 21:55:51 +0200 | Subject | Re: [PATCH 1/2] kasan: test: use underlying string helpers |
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On Mon, Oct 18, 2021 at 9:47 PM Kees Cook <keescook@chromium.org> wrote: > On Wed, Oct 13, 2021 at 05:00:05PM +0200, 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. > > Is this with W=1 ? I had explicitly disabled the read overflows for > "phase 1" of the overflow restriction tightening...
I have a somewhat modified source tree that builds cleanly with W=1 after disabling all the noisy ones, so this is probably one that I would not have seen without it.
> (And what do you think of using OPTIMIZER_HIDE_VAR() instead[1]? > > [1] https://lore.kernel.org/linux-hardening/20211006181544.1670992-1-keescook@chromium.org/T/#u
Yes, that is probably better. I can try updating the patch tomorrow, unless you do it first.
Arnd
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