From 3e2e3deed8dceb6b72bb2318b65d816197a30801 Mon Sep 17 00:00:00 2001
From: Mauro Carvalho Chehab <mchehab@kernel.org>
Date: Thu, 24 Mar 2022 17:59:11 +0100
Subject: [PATCH] Prevent crashes on device changes with control window opened

Changing the device without closing the control window
will cause crashes, as the newer device will very likely have
different settings.

Protect any changes at the camera control window with a
mutex and close the control window on a safe way, on
device changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/src/callbacks.c b/src/callbacks.c
index 3cd5222bb51d..a7a6b528e72a 100644
--- a/src/callbacks.c
+++ b/src/callbacks.c
@@ -870,7 +870,9 @@ static void reset_ctrls(GtkButton *btn, cam_t *cam)
 
 static void close_controls(GtkWidget* widget, cam_t *cam)
 {
+    g_mutex_lock(&cam->control_win_mutex);
     cam->controls_window = NULL;
+    g_mutex_unlock(&cam->control_win_mutex);
 }
 
 void show_controls(GtkWidget *widget, cam_t *cam)
@@ -982,7 +984,9 @@ void show_controls(GtkWidget *widget, cam_t *cam)
     g_signal_connect(G_OBJECT(window), "destroy",
                      G_CALLBACK (close_controls), cam);
 
+    g_mutex_lock(&cam->control_win_mutex);
     cam->controls_window = window;
+    g_mutex_unlock(&cam->control_win_mutex);
 
     gtk_widget_show_all(window);
 }
@@ -1150,8 +1154,10 @@ void contrast_change(GtkScale *sc1, cam_t *cam)
     cam->contrast = gtk_range_get_value((GtkRange *) sc1);
     cam_set_control(cam, V4L2_CID_CONTRAST, &cam->contrast);
 
+    g_mutex_lock(&cam->control_win_mutex);
     if (cam->controls_window)
         gtk_container_forall(GTK_CONTAINER(cam->controls_window), send_update_signal, 0);
+    g_mutex_unlock(&cam->control_win_mutex);
 }
 
 void brightness_change(GtkScale *sc1, cam_t *cam)
@@ -1160,8 +1166,10 @@ void brightness_change(GtkScale *sc1, cam_t *cam)
     cam->brightness = gtk_range_get_value((GtkRange *) sc1);
     cam_set_control(cam, V4L2_CID_BRIGHTNESS, &cam->brightness);
 
+    g_mutex_lock(&cam->control_win_mutex);
     if (cam->controls_window)
         gtk_container_forall(GTK_CONTAINER(cam->controls_window), send_update_signal, 0);
+    g_mutex_unlock(&cam->control_win_mutex);
 }
 
 void zoom_change(GtkScale *sc1, cam_t *cam)
@@ -1180,8 +1188,10 @@ void colour_change(GtkScale *sc1, cam_t *cam)
     cam->colour = gtk_range_get_value((GtkRange *) sc1);
     cam_set_control(cam, V4L2_CID_SATURATION, &cam->colour);
 
+    g_mutex_lock(&cam->control_win_mutex);
     if (cam->controls_window)
         gtk_container_forall(GTK_CONTAINER(cam->controls_window), send_update_signal, 0);
+    g_mutex_unlock(&cam->control_win_mutex);
 }
 
 void hue_change(GtkScale *sc1, cam_t *cam)
@@ -1190,8 +1200,10 @@ void hue_change(GtkScale *sc1, cam_t *cam)
     cam->hue = gtk_range_get_value((GtkRange *) sc1);
     cam_set_control(cam, V4L2_CID_HUE, &cam->hue);
 
+    g_mutex_lock(&cam->control_win_mutex);
     if (cam->controls_window)
         gtk_container_forall(GTK_CONTAINER(cam->controls_window), send_update_signal, 0);
+    g_mutex_unlock(&cam->control_win_mutex);
 }
 
 void wb_change(GtkScale *sc1, cam_t *cam)
@@ -1200,8 +1212,10 @@ void wb_change(GtkScale *sc1, cam_t *cam)
     cam->whiteness = gtk_range_get_value((GtkRange *) sc1);
     cam_set_control(cam, V4L2_CID_WHITENESS, &cam->whiteness);
 
+    g_mutex_lock(&cam->control_win_mutex);
     if (cam->controls_window)
         gtk_container_forall(GTK_CONTAINER(cam->controls_window), send_update_signal, 0);
+    g_mutex_unlock(&cam->control_win_mutex);
 }
 
 /*
@@ -1409,6 +1423,7 @@ int select_video_dev(cam_t *cam)
 
 void on_change_camera(GtkWidget *widget, cam_t *cam)
 {
+    GtkWidget *window;
     gchar *old_cam;
 
     old_cam = g_strdup(cam->video_dev);
@@ -1421,6 +1436,16 @@ void on_change_camera(GtkWidget *widget, cam_t *cam)
     }
     g_free(old_cam);
 
+    g_mutex_lock(&cam->control_win_mutex);
+    if (cam->controls_window) {
+        window = cam->controls_window;
+        cam->controls_window = NULL;
+        g_mutex_unlock(&cam->control_win_mutex);
+        gtk_window_close(GTK_WINDOW(window));
+    } else {
+        g_mutex_unlock(&cam->control_win_mutex);
+    }
+
     start_camera(cam);
     update_sliders(cam);
 }
diff --git a/src/main.c b/src/main.c
index 2f18136086d8..d8ef8b868f94 100644
--- a/src/main.c
+++ b/src/main.c
@@ -107,6 +107,7 @@ static void activate(GtkApplication *app)
     cam->app = app;
     g_mutex_init(&cam->remote_save_mutex);
     g_mutex_init(&cam->pixbuf_mutex);
+    g_mutex_init(&cam->control_win_mutex);
 
     /* gtk is initialized now */
     camorama_filters_init();
diff --git a/src/v4l.h b/src/v4l.h
index d432e1564bb9..cc69875c280c 100644
--- a/src/v4l.h
+++ b/src/v4l.h
@@ -103,6 +103,7 @@ typedef struct camera {
 
     GMutex remote_save_mutex;      /* Protects n_threads */
     GMutex pixbuf_mutex;           /* Protects pic_buf */
+    GMutex control_win_mutex;      /* Protects controls_window */
 
     unsigned int min_width, min_height, max_width, max_height;
     struct colorspace_parms colorspc;