[PATCH v2] kasan: turn on -fsanitize-address-use-after-scope

[Andrey Ryabinin]

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.

Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
Changes since v1:
   - s/release release/relase in changelog
   - added Ack

 scripts/Makefile.kasan | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 37323b0..9576775 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -28,4 +28,6 @@ else
         CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL)
     endif
 endif
+
+CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
 endif
-- 
2.7.3