Fix memcpy null arg UB

Author: nikic

ext/standard/http.c

@@ -130,8 +130,10 @@ PHPAPI int php_url_encode_hash_ex(HashTable *ht, smart_str *formstr,
 p += key_prefix_len;
 }
 
-memcpy(p, num_prefix, num_prefix_len);
-p += num_prefix_len;
+if (num_prefix) {
+memcpy(p, num_prefix, num_prefix_len);
+p += num_prefix_len;
+}
 
 memcpy(p, ekey, ekey_len);
 p += ekey_len;
@@ -162,7 +164,9 @@ PHPAPI int php_url_encode_hash_ex(HashTable *ht, smart_str *formstr,
 smart_str_appendl(formstr, arg_sep, arg_sep_len);
 }
 /* Simple key=value */
-smart_str_appendl(formstr, key_prefix, key_prefix_len);
+if (key_prefix) {
+smart_str_appendl(formstr, key_prefix, key_prefix_len);
+}
 if (key) {
 zend_string *ekey;
 if (enc_type == PHP_QUERY_RFC3986) {
@@ -179,7 +183,9 @@ PHPAPI int php_url_encode_hash_ex(HashTable *ht, smart_str *formstr,
 }
 smart_str_append_long(formstr, idx);
 }
-smart_str_appendl(formstr, key_suffix, key_suffix_len);
+if (key_suffix) {
+smart_str_appendl(formstr, key_suffix, key_suffix_len);
+}
 smart_str_appendl(formstr, "=", 1);
 switch (Z_TYPE_P(zdata)) {
 case IS_STRING: {