--- zzzz-none-000/linux-3.10.107/arch/x86/lib/usercopy_64.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/x86/lib/usercopy_64.c	2021-02-04 17:41:59.000000000 +0000
@@ -68,22 +68,21 @@
  * Since protection fault in copy_from/to_user is not a normal situation,
  * it is not necessary to optimize tail handling.
  */
-unsigned long
-copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
+__visible unsigned long
+copy_user_handle_tail(char *to, char *from, unsigned len)
 {
-	char c;
-	unsigned zero_len;
-
 	for (; len; --len, to++) {
+		char c;
+
 		if (__get_user_nocheck(c, from++, sizeof(char)))
 			break;
 		if (__put_user_nocheck(c, to, sizeof(char)))
 			break;
 	}
-
-	for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
-		if (__put_user_nocheck(c, to++, sizeof(char)))
-			break;
 	clac();
+
+	/* If the destination is a kernel buffer, we always clear the end */
+	if (!__addr_ok(to))
+		memset(to, 0, len);
 	return len;
 }