mips: copy_from_user() must zero the destination on access_ok() failure

commit e69d7005 upstream.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

arch/mips/include/asm/uaccess.h

@@ -13,6 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/thread_info.h>
+#include <linux/string.h>
 
 /*
  * The fs value determines whether argument validity checking should be
@@ -938,6 +939,8 @@ extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n);
 		might_fault();						\
 		__cu_len = __invoke_copy_from_user(__cu_to, __cu_from,	\
 						   __cu_len);		\
+	} else {							\
+		memset(__cu_to, 0, __cu_len);				\
 	}								\
 	__cu_len;							\
 })