Re: [PATCH 4.9 09/62] kasan: turn on -fsanitize-address-use-after-scope

[Greg Kroah-Hartman]

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 <aryabinin@xxxxxxxxxxxxx>
> > 
> > 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-aryabinin@xxxxxxxxxxxxx
> > Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> > Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> > Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> > Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > 
> > ---
> >  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?

thanks,

greg k-h