From b2fa4970fd57773f5f3353fa64af6a3480177009 Mon Sep 17 00:00:00 2001
From: "alexey.lysiuk" <alexey.lysiuk@gmail.com>
Date: Wed, 16 Sep 2015 16:13:56 +0300
Subject: [PATCH] Fixed potential crash in ACS engine

Unknown p-code in compiled script may lead to a crash if the current module was changed during script execution, e.g. by function call
See http://forum.zdoom.org/viewtopic.php?f=2&t=48524
---
 src/p_acs.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index b85ae28e1..f4d148d09 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -6032,6 +6032,7 @@ int DLevelScript::RunScript ()
 	int sp = 0;
 	int *pc = this->pc;
 	ACSFormat fmt = activeBehavior->GetFormat();
+	FBehavior* const savedActiveBehavior = activeBehavior;
 	unsigned int runaway = 0;	// used to prevent infinite loops
 	int pcd;
 	FString work;
@@ -6065,6 +6066,7 @@ int DLevelScript::RunScript ()
 		{
 		default:
 			Printf ("Unknown P-Code %d in %s\n", pcd, ScriptPresentation(script).GetChars());
+			activeBehavior = savedActiveBehavior;
 			// fall through
 		case PCD_TERMINATE:
 			DPrintf ("%s finished\n", ScriptPresentation(script).GetChars());