From: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Date: Tue, 29 Jun 2021 02:40:58 +0000 (-0700)
Subject: kasan: add memory corruption identification support for hardware tag-based mode
X-Git-Tag: accepted/tizen/unified/20230118.172025~6963^2~45
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7a22bdc3c443d5abc420df1381e425b49e8901a3;p=platform%2Fkernel%2Flinux-rpi.git

kasan: add memory corruption identification support for hardware tag-based mode

Add memory corruption identification support for hardware tag-based mode.
We store one old free pointer tag and free backtrace instead of five
because hardware tag-based kasan only has 16 different tags.

If we store as many stacks as SW tag-based kasan does(5 stacks), there is
high probability to find the same tag in the stacks when out-of-bound
issues happened and we will mistake out-of-bound issue for use-after-free.

Link: https://lkml.kernel.org/r/20210626100931.22794-4-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Nicholas Tang <nicholas.tang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index fdb4a08d..1e2d10f 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -169,7 +169,7 @@ config KASAN_STACK
 
 config KASAN_TAGS_IDENTIFY
 	bool "Enable memory corruption identification"
-	depends on KASAN_SW_TAGS
+	depends on KASAN_SW_TAGS || KASAN_HW_TAGS
 	help
 	  This option enables best-effort identification of bug type
 	  (use-after-free or out-of-bounds) at the cost of increased
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 2317d09..98e3059 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -153,7 +153,7 @@ struct kasan_track {
 	depot_stack_handle_t stack;
 };
 
-#ifdef CONFIG_KASAN_TAGS_IDENTIFY
+#if defined(CONFIG_KASAN_TAGS_IDENTIFY) && defined(CONFIG_KASAN_SW_TAGS)
 #define KASAN_NR_FREE_STACKS 5
 #else
 #define KASAN_NR_FREE_STACKS 1