Fix GH-16592 msg_send() crashes when the type does not serialize as expected.

It is assumed that the serialization always had initialised its buffer
zend_string, but in the case of a type not serialising, it is null.

close GH-16599

Author: devnexen

NEWS

@@ -129,6 +129,10 @@ PHP                                                                        NEWS
   . Fixed bug GH-16293 (Failed assertion when throwing in assert() callback with
     bail enabled). (ilutov)
 
+- SysVMsg:
+  . Fixed bug GH-16592 (msg_send() crashes when a type does not properly
+    serialized). (David Carlier / cmb)
+
 - SysVShm:
   . Fixed bug GH-16591 (Assertion error in shm_put_var). (nielsdos, cmb)
 

ext/sysvmsg/sysvmsg.c

@@ -371,11 +371,19 @@ PHP_FUNCTION(msg_send)
 		php_var_serialize(&msg_var, message, &var_hash);
 		PHP_VAR_SERIALIZE_DESTROY(var_hash);
 
+		if (UNEXPECTED(EG(exception))) {
+			smart_str_free(&msg_var);
+			RETURN_THROWS();
+		}
+
+
+		zend_string *str = smart_str_extract(&msg_var);
+		message_len = ZSTR_LEN(str);
 		/* NB: php_msgbuf is 1 char bigger than a long, so there is no need to
 		 * allocate the extra byte. */
-		messagebuffer = safe_emalloc(ZSTR_LEN(msg_var.s), 1, sizeof(struct php_msgbuf));
-		memcpy(messagebuffer->mtext, ZSTR_VAL(msg_var.s), ZSTR_LEN(msg_var.s) + 1);
-		message_len = ZSTR_LEN(msg_var.s);
+		messagebuffer = safe_emalloc(message_len, 1, sizeof(struct php_msgbuf));
+		memcpy(messagebuffer->mtext, ZSTR_VAL(str), message_len + 1);
+		zend_string_release_ex(str, false);
 		smart_str_free(&msg_var);
 	} else {
 		char *p;

ext/sysvmsg/tests/gh16592.phpt

@@ -0,0 +1,19 @@
+--TEST--
+msg_send() segfault when the type does not serialize as expected
+--EXTENSIONS--
+sysvmsg
+--FILE--
+<?php
+class Test {
+    function __serialize() {}
+}
+
+$q = msg_get_queue(1);
+try {
+	msg_send($q, 1, new Test, true);
+} catch (\TypeError $e) {
+	echo $e->getMessage();
+}
+?>
+--EXPECT--
+Test::__serialize() must return an array