mm/kasan: change kasan_check_{read,write} to return boolean

This changes {,__}kasan_check_{read,write} functions to return a boolean
denoting if the access was valid or not.

[sfr@canb.auug.org.au: include types.h for "bool"]
  Link: http://lkml.kernel.org/r/20190705184949.13cdd021@canb.auug.org.au
Link: http://lkml.kernel.org/r/20190626142014.141844-3-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/kasan-checks.h

@@ -2,19 +2,25 @@
 #ifndef _LINUX_KASAN_CHECKS_H
 #define _LINUX_KASAN_CHECKS_H
 
+#include <linux/types.h>
+
 /*
  * __kasan_check_*: Always available when KASAN is enabled. This may be used
  * even in compilation units that selectively disable KASAN, but must use KASAN
  * to validate access to an address.   Never use these in header files!
  */
 #ifdef CONFIG_KASAN
-void __kasan_check_read(const volatile void *p, unsigned int size);
-void __kasan_check_write(const volatile void *p, unsigned int size);
+bool __kasan_check_read(const volatile void *p, unsigned int size);
+bool __kasan_check_write(const volatile void *p, unsigned int size);
 #else
-static inline void __kasan_check_read(const volatile void *p, unsigned int size)
-{ }
-static inline void __kasan_check_write(const volatile void *p, unsigned int size)
-{ }
+static inline bool __kasan_check_read(const volatile void *p, unsigned int size)
+{
+	return true;
+}
+static inline bool __kasan_check_write(const volatile void *p, unsigned int size)
+{
+	return true;
+}
 #endif
 
 /*
@@ -25,10 +31,14 @@ static inline void __kasan_check_write(const volatile void *p, unsigned int size
 #define kasan_check_read __kasan_check_read
 #define kasan_check_write __kasan_check_write
 #else
-static inline void kasan_check_read(const volatile void *p, unsigned int size)
-{ }
-static inline void kasan_check_write(const volatile void *p, unsigned int size)
-{ }
+static inline bool kasan_check_read(const volatile void *p, unsigned int size)
+{
+	return true;
+}
+static inline bool kasan_check_write(const volatile void *p, unsigned int size)
+{
+	return true;
+}
 #endif
 
 #endif

mm/kasan/common.c

@@ -87,15 +87,15 @@ void kasan_disable_current(void)
 	current->kasan_depth--;
 }
 
-void __kasan_check_read(const volatile void *p, unsigned int size)
+bool __kasan_check_read(const volatile void *p, unsigned int size)
 {
-	check_memory_region((unsigned long)p, size, false, _RET_IP_);
+	return check_memory_region((unsigned long)p, size, false, _RET_IP_);
 }
 EXPORT_SYMBOL(__kasan_check_read);
 
-void __kasan_check_write(const volatile void *p, unsigned int size)
+bool __kasan_check_write(const volatile void *p, unsigned int size)
 {
-	check_memory_region((unsigned long)p, size, true, _RET_IP_);
+	return check_memory_region((unsigned long)p, size, true, _RET_IP_);
 }
 EXPORT_SYMBOL(__kasan_check_write);
 

mm/kasan/generic.c

@@ -166,29 +166,30 @@ static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
 	return memory_is_poisoned_n(addr, size);
 }
 
-static __always_inline void check_memory_region_inline(unsigned long addr,
+static __always_inline bool check_memory_region_inline(unsigned long addr,
 						size_t size, bool write,
 						unsigned long ret_ip)
 {
 	if (unlikely(size == 0))
-		return;
+		return true;
 
 	if (unlikely((void *)addr <
 		kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
 		kasan_report(addr, size, write, ret_ip);
-		return;
+		return false;
 	}
 
 	if (likely(!memory_is_poisoned(addr, size)))
-		return;
+		return true;
 
 	kasan_report(addr, size, write, ret_ip);
+	return false;
 }
 
-void check_memory_region(unsigned long addr, size_t size, bool write,
+bool check_memory_region(unsigned long addr, size_t size, bool write,
 				unsigned long ret_ip)
 {
-	check_memory_region_inline(addr, size, write, ret_ip);
+	return check_memory_region_inline(addr, size, write, ret_ip);
 }
 
 void kasan_cache_shrink(struct kmem_cache *cache)

mm/kasan/kasan.h

@@ -128,7 +128,15 @@ static inline bool addr_has_shadow(const void *addr)
 
 void kasan_poison_shadow(const void *address, size_t size, u8 value);
 
-void check_memory_region(unsigned long addr, size_t size, bool write,
+/**
+ * check_memory_region - Check memory region, and report if invalid access.
+ * @addr: the accessed address
+ * @size: the accessed size
+ * @write: true if access is a write access
+ * @ret_ip: return address
+ * @return: true if access was valid, false if invalid
+ */
+bool check_memory_region(unsigned long addr, size_t size, bool write,
 				unsigned long ret_ip);
 
 void *find_first_bad_addr(void *addr, size_t size);

mm/kasan/tags.c

@@ -76,15 +76,15 @@ void *kasan_reset_tag(const void *addr)
 	return reset_tag(addr);
 }
 
-void check_memory_region(unsigned long addr, size_t size, bool write,
+bool check_memory_region(unsigned long addr, size_t size, bool write,
 				unsigned long ret_ip)
 {
 	u8 tag;
 	u8 *shadow_first, *shadow_last, *shadow;
 	void *untagged_addr;
 
 	if (unlikely(size == 0))
-		return;
+		return true;
 
 	tag = get_tag((const void *)addr);
 
@@ -106,22 +106,24 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
 	 * set to KASAN_TAG_KERNEL (0xFF)).
 	 */
 	if (tag == KASAN_TAG_KERNEL)
-		return;
+		return true;
 
 	untagged_addr = reset_tag((const void *)addr);
 	if (unlikely(untagged_addr <
 			kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
 		kasan_report(addr, size, write, ret_ip);
-		return;
+		return false;
 	}
 	shadow_first = kasan_mem_to_shadow(untagged_addr);
 	shadow_last = kasan_mem_to_shadow(untagged_addr + size - 1);
 	for (shadow = shadow_first; shadow <= shadow_last; shadow++) {
 		if (*shadow != tag) {
 			kasan_report(addr, size, write, ret_ip);
-			return;
+			return false;
 		}
 	}
+
+	return true;
 }
 
 #define DEFINE_HWASAN_LOAD_STORE(size)					\