From 589df0861fde876a3d6eb996ec4ff7d63c559c1e Mon Sep 17 00:00:00 2001
From: jsg <jsg@openbsd.org>
Date: Fri, 26 Feb 2021 14:10:26 +0000
Subject: [PATCH] record: Fix undefined memcpy in RecordAClientStateChange

From Adam Jackson
f44ac101c523a0439bd1a864850e3c1a4e154549 in xserver git

avoids a large number of malloc(0) calls
ok deraadt@ who had almost the same diff
---
 xserver/record/record.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xserver/record/record.c b/xserver/record/record.c
index 05d751ac2..e4b97c18c 100644
--- a/xserver/record/record.c
+++ b/xserver/record/record.c
@@ -2728,7 +2728,8 @@ RecordAClientStateChange(CallbackListPtr *pcbl, void *nulldata,
     case ClientStateRetained:  /* client disconnected */
 
         /* RecordDisableContext modifies contents of ppAllContexts. */
-        numContextsCopy = numContexts;
+        if (!(numContextsCopy = numContexts))
+            break;
         ppAllContextsCopy = xallocarray(numContextsCopy,
                                         sizeof(RecordContextPtr));
         assert(ppAllContextsCopy);