From 4821cc5fe36201c550520b80dc661ec4f45cae8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sami=20P=C3=B6nk=C3=A4nen?= <sami.ponkanen@gmail.com>
Date: Thu, 17 Mar 2022 12:29:11 +0200
Subject: [PATCH] GUACAMOLE-1555: Call openlog() after client plugin unload.
 This fixes segfaults from guacd_log() in cases where the client plugin has
 called openlog() with a non-NULL ident string.

---
 src/guacd/proc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/guacd/proc.c b/src/guacd/proc.c
index 9641ac05a..0d9c0c175 100644
--- a/src/guacd/proc.c
+++ b/src/guacd/proc.c
@@ -42,6 +42,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <syslog.h>
 
 /**
  * Parameters for the user thread.
@@ -353,6 +354,12 @@ static void guacd_exec_proc(guacd_proc* proc, const char* protocol) {
     guacd_log(GUAC_LOG_DEBUG, "Requesting termination of client...");
     result = guacd_timed_client_free(client, GUACD_CLIENT_FREE_TIMEOUT);
 
+    /* Reopen syslog now that client plugins have been unloaded. This fixes
+       guacd_log() segfaults in cases where the client plugins have called
+       openlog() causing syslog ident string to point to the plugin's
+       memory region. */
+    openlog(GUACD_LOG_NAME, LOG_PID, LOG_DAEMON);
+
     /* If client was unable to be freed, warn and forcibly kill */
     if (result) {
         guacd_log(GUAC_LOG_WARNING, "Client did not terminate in a timely "