From 78ca670d4f89ffa7f887f8f32d6d6e39bd9c78c3 Mon Sep 17 00:00:00 2001
From: Zack Middleton <zack@cloemail.com>
Date: Sun, 21 Jan 2018 03:50:43 -0600
Subject: [PATCH] Don't let VMs change engine latch cvars immediately

If a VM increases sv_maxclients while a server is running the engine
will crash. The value should be latched until engine decides to update
the cvar; the same as when a user sets it.
---
 code/qcommon/cvar.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/code/qcommon/cvar.c b/code/qcommon/cvar.c
index 5a0e6906..6f1ca432 100644
--- a/code/qcommon/cvar.c
+++ b/code/qcommon/cvar.c
@@ -638,18 +638,29 @@ Cvar_SetSafe
 void Cvar_SetSafe( const char *var_name, const char *value )
 {
 	int flags = Cvar_Flags( var_name );
+	qboolean force = qtrue;
 
-	if((flags != CVAR_NONEXISTENT) && (flags & CVAR_PROTECTED))
+	if ( flags != CVAR_NONEXISTENT )
 	{
-		if( value )
-			Com_Error( ERR_DROP, "Restricted source tried to set "
-				"\"%s\" to \"%s\"", var_name, value );
-		else
-			Com_Error( ERR_DROP, "Restricted source tried to "
-				"modify \"%s\"", var_name );
-		return;
+		if ( flags & CVAR_PROTECTED )
+		{
+			if( value )
+				Com_Error( ERR_DROP, "Restricted source tried to set "
+					"\"%s\" to \"%s\"", var_name, value );
+			else
+				Com_Error( ERR_DROP, "Restricted source tried to "
+					"modify \"%s\"", var_name );
+			return;
+		}
+
+		// don't let VMs or server change engine latched cvars instantly
+		if ( ( flags & CVAR_LATCH ) && !( flags & CVAR_VM_CREATED ) )
+		{
+			force = qfalse;
+		}
 	}
-	Cvar_Set( var_name, value );
+
+	Cvar_Set2 (var_name, value, force);
 }
 
 /*