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

[Greg Kroah-Hartman]

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