[PATCH v4 2/5] mm/kasan: Change kasan_check_{read,write} to return boolean

Marco Elver
2019-06-27T09:45:14Z

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

Signed-off-by: Marco Elver <elver@google.com>
Cc: 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: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
---
v3:
* Fix Formatting and split introduction of __kasan_check_* and returning
bool into 2 patches.
---
include/linux/kasan-checks.h | 36 ++++++++++++++++++++++--------------
mm/kasan/common.c | 8 ++++----
mm/kasan/generic.c | 13 +++++++------
mm/kasan/kasan.h | 10 +++++++++-
mm/kasan/tags.c | 12 +++++++-----
5 files changed, 49 insertions(+), 30 deletions(-)

diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
index 19a0175d2452..2c7f0b6307b2 100644
--- a/include/linux/kasan-checks.h
+++ b/include/linux/kasan-checks.h
@@ -8,13 +8,17 @@
* 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

/*
@@ -22,19 +26,23 @@ static inline void __kasan_check_write(const volatile void *p, unsigned int size
* instrumentation enabled. May be used in header files.
*/
#ifdef __SANITIZE_ADDRESS__
-static inline void kasan_check_read(const volatile void *p, unsigned int size)
+static inline bool kasan_check_read(const volatile void *p, unsigned int size)
{
- __kasan_check_read(p, size);
+ return __kasan_check_read(p, size);
}
-static inline void kasan_check_write(const volatile void *p, unsigned int size)
+static inline bool kasan_check_write(const volatile void *p, unsigned int size)
{
- __kasan_check_read(p, size);
+ return __kasan_check_read(p, 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

#endif
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 6bada42cc152..2277b82902d8 100644
--- a/mm/kasan/common.c
+++ b/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);

diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 504c79363a34..616f9dd82d12 100644
--- a/mm/kasan/generic.c
+++ b/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)
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 3ce956efa0cb..e62ea45d02e3 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -123,7 +123,15 @@ 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);
diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 63fca3172659..0e987c9ca052 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -76,7 +76,7 @@ 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;
@@ -84,7 +84,7 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
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) \
--
2.22.0.410.gd8fdbe21b5-goog