Bug 646227 — Possible overflow in persona-view:drag_data_get

I think it was a fluke that this code worked in the first place, since it was
accessing arrays with indices which were out of range, and which wouldn't have
corresponded to the correct entries even if they were in range.

This should fix the mapping between DND types and DND URIs/atoms in the
contact list, individual and persona views.

Closes: bgo#646227

3 files changed, 43 insertions, 40 deletions

diff --git a/libempathy-gtk/empathy-contact-list-view.c b/libempathy-gtk/empathy-contact-list-view.c
index 79eb5a316..bda1ed8d5 100644
--- a/libempathy-gtk/empathy-contact-list-view.c
+++ b/libempathy-gtk/empathy-contact-list-view.c
@@ -112,9 +112,6 @@ static const GtkTargetEntry drag_types_source[] = {
 	{ "text/contact-id", 0, DND_DRAG_TYPE_CONTACT_ID },
 };
 
-static GdkAtom drag_atoms_dest[G_N_ELEMENTS (drag_types_dest)];
-static GdkAtom drag_atoms_source[G_N_ELEMENTS (drag_types_source)];
-
 enum {
 	DRAG_CONTACT_RECEIVED,
 	LAST_SIGNAL
@@ -763,7 +760,8 @@ contact_list_view_drag_data_get (GtkWidget        *widget,
 	str = g_strconcat (account_id, ":", contact_id, NULL);
 
 	if (info == DND_DRAG_TYPE_CONTACT_ID) {
-		gtk_selection_data_set (selection, drag_atoms_source[info], 8,
+		gtk_selection_data_set (selection,
+					gdk_atom_intern ("text/contact-id", FALSE), 8,
 					(guchar *) str, strlen (str) + 1);
 	}
 
@@ -1497,7 +1495,6 @@ contact_list_view_constructed (GObject *object)
 	EmpathyContactListViewPriv *priv = GET_PRIV (view);
 	GtkCellRenderer            *cell;
 	GtkTreeViewColumn          *col;
-	guint                       i;
 
 	priv->filter = GTK_TREE_MODEL_FILTER (gtk_tree_model_filter_new (
 			GTK_TREE_MODEL (priv->store), NULL));
@@ -1629,17 +1626,6 @@ contact_list_view_constructed (GObject *object)
 
 	/* Actually add the column now we have added all cell renderers */
 	gtk_tree_view_append_column (GTK_TREE_VIEW (view), col);
-
-	/* Drag & Drop. */
-	for (i = 0; i < G_N_ELEMENTS (drag_types_dest); ++i) {
-		drag_atoms_dest[i] = gdk_atom_intern (drag_types_dest[i].target,
-						      FALSE);
-	}
-
-	for (i = 0; i < G_N_ELEMENTS (drag_types_source); ++i) {
-		drag_atoms_source[i] = gdk_atom_intern (drag_types_source[i].target,
-							FALSE);
-	}
 }
 
 static void
diff --git a/libempathy-gtk/empathy-individual-view.c b/libempathy-gtk/empathy-individual-view.c
index 90a9fc6db..98c7f96d1 100644
--- a/libempathy-gtk/empathy-individual-view.c
+++ b/libempathy-gtk/empathy-individual-view.c
@@ -110,13 +110,14 @@ enum
 
 /* TODO: re-add DRAG_TYPE_CONTACT_ID, for the case that we're dragging around
  * specific EmpathyContacts (between/in/out of Individuals) */
-enum DndDragType
+typedef enum
 {
-  DND_DRAG_TYPE_INDIVIDUAL_ID,
+  DND_DRAG_TYPE_UNKNOWN = -1,
+  DND_DRAG_TYPE_INDIVIDUAL_ID = 0,
   DND_DRAG_TYPE_PERSONA_ID,
   DND_DRAG_TYPE_URI_LIST,
   DND_DRAG_TYPE_STRING,
-};
+} DndDragType;
 
 #define DRAG_TYPE(T,I) \
   { (gchar *) T, 0, I }
@@ -137,7 +138,6 @@ static const GtkTargetEntry drag_types_source[] = {
 #undef DRAG_TYPE
 
 static GdkAtom drag_atoms_dest[G_N_ELEMENTS (drag_types_dest)];
-static GdkAtom drag_atoms_source[G_N_ELEMENTS (drag_types_source)];
 
 enum
 {
@@ -565,6 +565,8 @@ individual_view_drag_motion (GtkWidget *widget,
   gboolean is_different = FALSE;
   gboolean cleanup = TRUE;
   gboolean retval = TRUE;
+  guint i;
+  DndDragType drag_type = DND_DRAG_TYPE_UNKNOWN;
 
   priv = GET_PRIV (EMPATHY_INDIVIDUAL_VIEW (widget));
   model = gtk_tree_view_get_model (GTK_TREE_VIEW (widget));
@@ -595,8 +597,18 @@ individual_view_drag_motion (GtkWidget *widget,
   target = gtk_drag_dest_find_target (widget, context, NULL);
   gtk_tree_model_get_iter (model, &iter, path);
 
-  if (target == drag_atoms_dest[DND_DRAG_TYPE_URI_LIST] ||
-      target == drag_atoms_dest[DND_DRAG_TYPE_STRING])
+  /* Determine the DndDragType of the data */
+  for (i = 0; i < G_N_ELEMENTS (drag_atoms_dest); i++)
+    {
+      if (target == drag_atoms_dest[i])
+        {
+          drag_type = drag_types_dest[i].info;
+          break;
+        }
+    }
+
+  if (drag_type == DND_DRAG_TYPE_URI_LIST ||
+      drag_type == DND_DRAG_TYPE_STRING)
     {
       /* This is a file drag, and it can only be dropped on contacts,
        * not groups.
@@ -641,10 +653,10 @@ individual_view_drag_motion (GtkWidget *widget,
       if (individual != NULL)
         g_object_unref (individual);
     }
-  else if ((target == drag_atoms_dest[DND_DRAG_TYPE_INDIVIDUAL_ID] &&
+  else if ((drag_type == DND_DRAG_TYPE_INDIVIDUAL_ID &&
       (priv->view_features & EMPATHY_INDIVIDUAL_VIEW_FEATURE_GROUPS_CHANGE ||
        priv->drag_row == NULL)) ||
-      (target == drag_atoms_dest[DND_DRAG_TYPE_PERSONA_ID] &&
+      (drag_type == DND_DRAG_TYPE_PERSONA_ID &&
        priv->view_features & EMPATHY_INDIVIDUAL_VIEW_FEATURE_PERSONA_DROP))
     {
       /* If target != GDK_NONE, then we have a contact (individual or persona)
@@ -789,7 +801,8 @@ individual_view_drag_data_get (GtkWidget *widget,
 
   if (info == DND_DRAG_TYPE_INDIVIDUAL_ID)
     {
-      gtk_selection_data_set (selection, drag_atoms_source[info], 8,
+      gtk_selection_data_set (selection,
+          gdk_atom_intern ("text/individual-id", FALSE), 8,
           (guchar *) individual_id, strlen (individual_id) + 1);
     }
 
@@ -1856,12 +1869,6 @@ individual_view_constructed (GObject *object)
     {
       drag_atoms_dest[i] = gdk_atom_intern (drag_types_dest[i].target, FALSE);
     }
-
-  for (i = 0; i < G_N_ELEMENTS (drag_types_source); ++i)
-    {
-      drag_atoms_source[i] = gdk_atom_intern (drag_types_source[i].target,
-          FALSE);
-    }
 }
 
 static void
diff --git a/libempathy-gtk/empathy-persona-view.c b/libempathy-gtk/empathy-persona-view.c
index adfe6be5c..ff2c6ec82 100644
--- a/libempathy-gtk/empathy-persona-view.c
+++ b/libempathy-gtk/empathy-persona-view.c
@@ -83,12 +83,13 @@ enum
   PROP_FEATURES,
 };
 
-enum DndDragType
+typedef enum
 {
-  DND_DRAG_TYPE_INDIVIDUAL_ID,
+  DND_DRAG_TYPE_UNKNOWN = -1,
+  DND_DRAG_TYPE_INDIVIDUAL_ID = 0,
   DND_DRAG_TYPE_PERSONA_ID,
   DND_DRAG_TYPE_STRING,
-};
+} DndDragType;
 
 #define DRAG_TYPE(T,I) \
   { (gchar *) T, 0, I }
@@ -106,7 +107,6 @@ static const GtkTargetEntry drag_types_source[] = {
 #undef DRAG_TYPE
 
 static GdkAtom drag_atoms_dest[G_N_ELEMENTS (drag_types_dest)];
-static GdkAtom drag_atoms_source[G_N_ELEMENTS (drag_types_source)];
 
 enum
 {
@@ -412,12 +412,24 @@ drag_motion (GtkWidget *widget,
   EmpathyPersonaView *self = EMPATHY_PERSONA_VIEW (widget);
   EmpathyPersonaViewPriv *priv;
   GdkAtom target;
+  guint i;
+  DndDragType drag_type = DND_DRAG_TYPE_UNKNOWN;
 
   priv = GET_PRIV (self);
 
   target = gtk_drag_dest_find_target (GTK_WIDGET (self), context, NULL);
 
-  if (target == drag_atoms_dest[DND_DRAG_TYPE_INDIVIDUAL_ID])
+  /* Determine the DndDragType of the data */
+  for (i = 0; i < G_N_ELEMENTS (drag_atoms_dest); i++)
+    {
+      if (target == drag_atoms_dest[i])
+        {
+          drag_type = drag_types_dest[i].info;
+          break;
+        }
+    }
+
+  if (drag_type == DND_DRAG_TYPE_INDIVIDUAL_ID)
     {
       GtkTreePath *path;
 
@@ -466,7 +478,8 @@ drag_data_get (GtkWidget *widget,
     return;
 
   persona_uid = folks_persona_get_uid (persona);
-  gtk_selection_data_set (selection, drag_atoms_source[info], 8,
+  gtk_selection_data_set (selection,
+      gdk_atom_intern ("text/persona-id", FALSE), 8,
       (guchar *) persona_uid, strlen (persona_uid) + 1);
 
   g_object_unref (persona);
@@ -614,9 +627,6 @@ constructed (GObject *object)
   /* Drag & Drop. */
   for (i = 0; i < G_N_ELEMENTS (drag_types_dest); ++i)
     drag_atoms_dest[i] = gdk_atom_intern (drag_types_dest[i].target, FALSE);
-
-  for (i = 0; i < G_N_ELEMENTS (drag_types_source); ++i)
-    drag_atoms_source[i] = gdk_atom_intern (drag_types_source[i].target, FALSE);
 }
 
 static void