Avoid segfault in CloseWellKnownConnections when using -displayfd

When -displayfd is looping through the possible display ids to use,
if it can't open all the listening sockets for one (say when :0 is
already in use), it calls CloseWellKnownConnections to close all
the ListenTransConns entries before the point that ListenTransFds
was allocated & initialized, so CloseWellKnownConnections would
segfault trying to read entries from a NULL ListenTransFds pointer.

Introduced by commit 7b02f0b8

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Keith Packard <keithp@keithp.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/os/connection.c b/os/connection.c
index 8e7513902..2a4fc8db8 100644
--- a/os/connection.c
+++ b/os/connection.c
@@ -523,7 +523,8 @@ CloseWellKnownConnections(void)
         if (ListenTransConns[i] != NULL) {
             _XSERVTransClose(ListenTransConns[i]);
             ListenTransConns[i] = NULL;
-            RemoveNotifyFd(ListenTransFds[i]);
+            if (ListenTransFds != NULL)
+                RemoveNotifyFd(ListenTransFds[i]);
         }
     }
     ListenTransCount = 0;