mm, kasan: don't call kasan_krealloc() from ksize().

Instead of calling kasan_krealloc(), which replaces the memory
allocation stack ID (if stack depot is used), just unpoison the whole
memory chunk.
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Konstantin Serebryany <kcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -4501,7 +4501,7 @@ size_t ksize(const void *objp)
 	/* We assume that ksize callers could use the whole allocated area,
 	 * so we need to unpoison this area.
 	 */
-	kasan_krealloc(objp, size, GFP_NOWAIT);
+	kasan_unpoison_shadow(objp, size);
 
 	return size;
 }

mm/slub.c

@@ -3635,8 +3635,9 @@ size_t ksize(const void *object)
 {
 	size_t size = __ksize(object);
 	/* We assume that ksize callers could use whole allocated area,
-	   so we need unpoison this area. */
-	kasan_krealloc(object, size, GFP_NOWAIT);
+	 * so we need to unpoison this area.
+	 */
+	kasan_unpoison_shadow(object, size);
 	return size;
 }
 EXPORT_SYMBOL(ksize);