On Mon, May 06, 2019 at 06:36:45PM +0300, Andrey Ryabinin wrote:
>
>
> On 5/6/19 6:10 PM, Greg Kroah-Hartman wrote:
> > On Mon, May 06, 2019 at 05:55:54PM +0300, Andrey Ryabinin wrote:
> >>
> >>
> >> On 5/6/19 5:32 PM, Greg Kroah-Hartman wrote:
> >>> From: Andrey Ryabinin <aryabi...@virtuozzo.com>
> >>>
> >>> commit c5caf21ab0cf884ef15b25af234f620e4a233139 upstream.
> >>>
> >>> In the upcoming gcc7 release, the -fsanitize=kernel-address option at
> >>> first implied new -fsanitize-address-use-after-scope option. This would
> >>> cause link errors on older kernels because they don't have two new
> >>> functions required for use-after-scope support. Therefore, gcc7 changed
> >>> default to -fno-sanitize-address-use-after-scope.
> >>>
> >>> Now the kernel has everything required for that feature since commit
> >>> 828347f8f9a5 ("kasan: support use-after-scope detection"). So, to make it
> >>> work, we just have to enable use-after-scope in CFLAGS.
> >>>
> >>> Link:
> >>> http://lkml.kernel.org/r/1481207977-28654-1-git-send-email-aryabi...@virtuozzo.com
> >>> Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
> >>> Acked-by: Dmitry Vyukov <dvyu...@google.com>
> >>> Cc: Alexander Potapenko <gli...@google.com>
> >>> Cc: Andrey Konovalov <andreyk...@google.com>
> >>> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
> >>> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
> >>> Signed-off-by: Andrey Konovalov <andreyk...@google.com>
> >>> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> >>>
> >>> ---
> >>> scripts/Makefile.kasan | 2 ++
> >>> 1 file changed, 2 insertions(+)
> >>>
> >>> --- a/scripts/Makefile.kasan
> >>> +++ b/scripts/Makefile.kasan
> >>> @@ -29,6 +29,8 @@ else
> >>> endif
> >>> endif
> >>>
> >>> +CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
> >>> +
> >>> CFLAGS_KASAN_NOSANITIZE := -fno-builtin
> >>>
> >>> endif
> >>>
> >>>
> >>
> >> This shouldn't be in the -stable.
> >
> > Why not? Does no one use gcc7 with this kernel and kasan?
> >
>
> You don't need this patch to use kasan on this kernel with gcc7.
> This patch only enables detection of use-after-scope bugs. This feature
> appeared to be useless,
> hence it disabled recently by commit 7771bdbbfd3d ("kasan: remove use after
> scope bugs detection.")
Ah, didn't notice that, nice!
Ok, I'll go drop this, thanks for letting me know.
> The link errors mentioned in changelog was the problem only for some period
> of time in the development branch of GCC 7.
> The released GCC7 version doesn't have this problem.
Also good to know, thanks!
greg k-h
