[PATCH v4.4 V2 09/43] mm/kasan: add API to check memory regions

[Viresh Kumar <viresh.kumar@linaro.org>]

From: Andrey Ryabinin <aryabinin@virtuozzo.com>

commit 64f8ebaf115bcddc4aaa902f981c57ba6506bc42 upstream.

Memory access coded in an assembly won't be seen by KASAN as a compiler
can instrument only C code.  Add kasan_check_[read,write]() API which is
going to be used to check a certain memory range.

Link: http://lkml.kernel.org/r/1462538722-1574-3-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ v4.4: Fixed MAINTAINERS conflict and added whole kasan entry. Drop 4th
	argument to check_memory_region(). ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 MAINTAINERS                  | 14 ++++++++++++++
 include/linux/kasan-checks.h | 12 ++++++++++++
 mm/kasan/kasan.c             | 12 ++++++++++++
 3 files changed, 38 insertions(+)
 create mode 100644 include/linux/kasan-checks.h

diff --git a/MAINTAINERS b/MAINTAINERS
index f4d4a5544dc1..2a8826732967 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5982,6 +5982,20 @@ S:	Maintained
 F:	Documentation/hwmon/k8temp
 F:	drivers/hwmon/k8temp.c
 
+KASAN
+M:	Andrey Ryabinin <aryabinin@virtuozzo.com>
+R:	Alexander Potapenko <glider@google.com>
+R:	Dmitry Vyukov <dvyukov@google.com>
+L:	kasan-dev@googlegroups.com
+S:	Maintained
+F:	arch/*/include/asm/kasan.h
+F:	arch/*/mm/kasan_init*
+F:	Documentation/kasan.txt
+F:	include/linux/kasan*.h
+F:	lib/test_kasan.c
+F:	mm/kasan/
+F:	scripts/Makefile.kasan
+
 KCONFIG
 M:	"Yann E. MORIN" <yann.morin.1998@free.fr>
 L:	linux-kbuild@vger.kernel.org
diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
new file mode 100644
index 000000000000..b7f8aced7870
--- /dev/null
+++ b/include/linux/kasan-checks.h
@@ -0,0 +1,12 @@
+#ifndef _LINUX_KASAN_CHECKS_H
+#define _LINUX_KASAN_CHECKS_H
+
+#ifdef CONFIG_KASAN
+void kasan_check_read(const void *p, unsigned int size);
+void kasan_check_write(const void *p, unsigned int size);
+#else
+static inline void kasan_check_read(const void *p, unsigned int size) { }
+static inline void kasan_check_write(const void *p, unsigned int size) { }
+#endif
+
+#endif
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index b7397b459960..1cdcab0c976a 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -274,6 +274,18 @@ static __always_inline void check_memory_region(unsigned long addr,
 void __asan_loadN(unsigned long addr, size_t size);
 void __asan_storeN(unsigned long addr, size_t size);
 
+void kasan_check_read(const void *p, unsigned int size)
+{
+	check_memory_region((unsigned long)p, size, false);
+}
+EXPORT_SYMBOL(kasan_check_read);
+
+void kasan_check_write(const void *p, unsigned int size)
+{
+	check_memory_region((unsigned long)p, size, true);
+}
+EXPORT_SYMBOL(kasan_check_write);
+
 #undef memset
 void *memset(void *addr, int c, size_t len)
 {
-- 
2.21.0.rc0.269.g1a574e7a288b