pstore: Replace calls to kmalloc and memcpy with kmemdup

Replaced calls to kmalloc and memcpy with a single call to kmemdup. This
patch was found using coccicheck.

Signed-off-by: Alexandru Gheorghiu <gheorghiuandru@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>

fs/pstore/ram.c

@@ -156,10 +156,9 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 	time->tv_nsec = 0;
 
 	size = persistent_ram_old_size(prz);
-	*buf = kmalloc(size, GFP_KERNEL);
+	*buf = kmemdup(persistent_ram_old(prz), size, GFP_KERNEL);
 	if (*buf == NULL)
 		return -ENOMEM;
-	memcpy(*buf, persistent_ram_old(prz), size);
 
 	return size;
 }