sparc32: fix copy_from_user()

commit 917400ce upstream.
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/sparc/include/asm/uaccess_32.h

@@ -265,8 +265,10 @@ static inline unsigned long copy_from_user(void *to, const void __user *from, un
 {
 	if (n && __access_ok((unsigned long) from, n))
 		return __copy_user((__force void __user *) to, from, n);
-	else
+	else {
+		memset(to, 0, n);
 		return n;
+	}
 }
 
 static inline unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n)