From 9f5686ef48956cd64ef92f737e59cbbaa27d8cf9 Mon Sep 17 00:00:00 2001
From: Louis-Antoine <lamr@free.fr>
Date: Mon, 26 Oct 2020 23:15:22 +0100
Subject: [PATCH] Fix underflow in consistancy checking code

---
 src/d_clisrv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/d_clisrv.c b/src/d_clisrv.c
index cc2715cb1..e671bced6 100644
--- a/src/d_clisrv.c
+++ b/src/d_clisrv.c
@@ -4067,7 +4067,7 @@ static void HandlePacketFromPlayer(SINT8 node)
 					&netbuffer->u.client2pak.cmd2, 1);
 
 			// Check player consistancy during the level
-			if (realstart <= gametic && realstart > gametic - BACKUPTICS+1 && gamestate == GS_LEVEL
+			if (realstart <= gametic && realstart + BACKUPTICS - 1 > gametic && gamestate == GS_LEVEL
 				&& consistancy[realstart%BACKUPTICS] != SHORT(netbuffer->u.clientpak.consistancy)
 				&& !resendingsavegame[node])
 			{