kasan: ensure poisoning size alignment

A previous changes d99f6a10c161 ("kasan: don't round_up too much")
attempted to simplify the code by adding a round_up(size) call into
kasan_poison().  While this allows to have less round_up() calls around
the code, this results in round_up() being called multiple times.

This patch removes round_up() of size from kasan_poison() and ensures that
all callers round_up() the size explicitly.  This patch also adds
WARN_ON() alignment checks for address and size to kasan_poison() and
kasan_unpoison().

Link: https://lkml.kernel.org/r/3ffe8d4a246ae67a8b5e91f65bf98cd7cba9d7b9.1612546384.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 13 deletions

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 222858e2e6af..8c55634d6edd 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -330,30 +330,37 @@ static inline u8 kasan_random_tag(void) { return 0; }
 
 #ifdef CONFIG_KASAN_HW_TAGS
 
-static inline void kasan_poison(const void *address, size_t size, u8 value)
+static inline void kasan_poison(const void *addr, size_t size, u8 value)
 {
-	address = kasan_reset_tag(address);
+	addr = kasan_reset_tag(addr);
 
 	/* Skip KFENCE memory if called explicitly outside of sl*b. */
-	if (is_kfence_address(address))
+	if (is_kfence_address(addr))
 		return;
 
-	hw_set_mem_tag_range((void *)address,
-			round_up(size, KASAN_GRANULE_SIZE), value);
+	if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
+		return;
+	if (WARN_ON(size & KASAN_GRANULE_MASK))
+		return;
+
+	hw_set_mem_tag_range((void *)addr, size, value);
 }
 
-static inline void kasan_unpoison(const void *address, size_t size)
+static inline void kasan_unpoison(const void *addr, size_t size)
 {
-	u8 tag = get_tag(address);
+	u8 tag = get_tag(addr);
 
-	address = kasan_reset_tag(address);
+	addr = kasan_reset_tag(addr);
 
 	/* Skip KFENCE memory if called explicitly outside of sl*b. */
-	if (is_kfence_address(address))
+	if (is_kfence_address(addr))
 		return;
 
-	hw_set_mem_tag_range((void *)address,
-			round_up(size, KASAN_GRANULE_SIZE), tag);
+	if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
+		return;
+	size = round_up(size, KASAN_GRANULE_SIZE);
+
+	hw_set_mem_tag_range((void *)addr, size, tag);
 }
 
 static inline bool kasan_byte_accessible(const void *addr)
@@ -370,7 +377,7 @@ static inline bool kasan_byte_accessible(const void *addr)
 /**
  * kasan_poison - mark the memory range as unaccessible
  * @addr - range start address, must be aligned to KASAN_GRANULE_SIZE
- * @size - range size
+ * @size - range size, must be aligned to KASAN_GRANULE_SIZE
  * @value - value that's written to metadata for the range
  *
  * The size gets aligned to KASAN_GRANULE_SIZE before marking the range.
@@ -380,7 +387,7 @@ void kasan_poison(const void *addr, size_t size, u8 value);
 /**
  * kasan_unpoison - mark the memory range as accessible
  * @addr - range start address, must be aligned to KASAN_GRANULE_SIZE
- * @size - range size
+ * @size - range size, can be unaligned
  *
  * For the tag-based modes, the @size gets aligned to KASAN_GRANULE_SIZE before
  * marking the range.