From 2cd233cd0c70ffa7ac4ca7ef2db400f920f2a468 Mon Sep 17 00:00:00 2001
From: Alex Leitner <leitnersalex@gmail.com>
Date: Sat, 9 Mar 2024 01:17:17 +0000
Subject: [PATCH] GUACAMOLE-1732: Prevent deadlock and enhance cleanup in RDP
 client.

---
 src/protocols/rdp/client.c | 10 +++++++++-
 src/protocols/rdp/rdp.c    | 12 ++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/protocols/rdp/client.c b/src/protocols/rdp/client.c
index e98a0f3a54..9090aee078 100644
--- a/src/protocols/rdp/client.c
+++ b/src/protocols/rdp/client.c
@@ -35,6 +35,7 @@
 #include "common-ssh/user.h"
 #endif
 
+#include <guacamole/argv.h>
 #include <guacamole/audio.h>
 #include <guacamole/client.h>
 #include <guacamole/mem.h>
@@ -241,6 +242,14 @@ int guac_rdp_client_free_handler(guac_client* client) {
 
     guac_rdp_client* rdp_client = (guac_rdp_client*) client->data;
 
+    /*
+     * Signals any threads that are blocked awaiting user input for authentication
+     * (e.g., username or password) to terminate their wait. By broadcasting a
+     * condition signal, the authentication process is interrupted, allowing for
+     * premature termination and cleanup during client disconnection.
+     */
+    guac_argv_stop();
+
     /* Wait for client thread */
     pthread_join(rdp_client->client_thread, NULL);
 
@@ -306,4 +315,3 @@ int guac_rdp_client_free_handler(guac_client* client) {
     return 0;
 
 }
-
diff --git a/src/protocols/rdp/rdp.c b/src/protocols/rdp/rdp.c
index 1a16780b5f..2c00cf6c5c 100644
--- a/src/protocols/rdp/rdp.c
+++ b/src/protocols/rdp/rdp.c
@@ -525,12 +525,24 @@ static int guac_rdp_handle_connection(guac_client* client) {
     /* Set default pointer */
     guac_common_cursor_set_pointer(rdp_client->display->cursor);
 
+    /* 
+     * Downgrade the lock to allow for concurrent read access
+     * Access to read locks need to be made available for other processes to use 
+     * while we await credentials from the user.
+     */
+    pthread_rwlock_unlock(&(rdp_client->lock));
+    pthread_rwlock_rdlock(&(rdp_client->lock));
+
     /* Connect to RDP server */
     if (!freerdp_connect(rdp_inst)) {
         guac_rdp_client_abort(client, rdp_inst);
         goto fail;
     }
 
+    /* Upgrade to write lock again for further exclusive operations */
+    pthread_rwlock_unlock(&(rdp_client->lock));
+    pthread_rwlock_wrlock(&(rdp_client->lock));
+
     /* Connection complete */
     rdp_client->rdp_inst = rdp_inst;