[gnome-calendar/mcatanzaro/#434-gnome-3-32] Don't leave dangling pointers in the GcalEvent cache

[Michael Catanzaro <mcatanzaro src gnome org>]

commit acd6f57e2121edcb6625ff02042e8c5b799b9d98
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sun Jul 21 13:38:40 2019 -0500

    Don't leave dangling pointers in the GcalEvent cache
    
    The cache has an unowned pointer to the GcalEvent's UID. We need to
    update the cache with the GcalEvent's new UID to avoid use-after-free.
    
    Fixes #434

 src/gcal-event.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)
---
diff --git a/src/gcal-event.c b/src/gcal-event.c
index e8eada98..07c74222 100644
--- a/src/gcal-event.c
+++ b/src/gcal-event.c
@@ -259,13 +259,19 @@ gcal_event_update_uid_internal (GcalEvent *self)
 {
   ECalComponentId *id;
   const gchar *source_id;
+  gboolean should_update_cache = FALSE;
 
   /* Setup event uid */
   source_id = self->source ? e_source_get_uid (self->source) : "";
   id = e_cal_component_get_id (self->component);
 
-  /* Clear the previous uid */
-  g_clear_pointer (&self->uid, g_free);
+  if (self->uid != NULL)
+    {
+      should_update_cache = TRUE;
+      g_debug ("Removing '%s' (%p) from cache", self->uid, self);
+      g_hash_table_remove (event_cache, self->uid);
+      g_free (self->uid);
+    }
 
   if (id->rid != NULL)
     {
@@ -281,6 +287,12 @@ gcal_event_update_uid_internal (GcalEvent *self)
                                    id->uid);
     }
 
+  if (should_update_cache)
+    {
+      g_debug ("Adding %s to the cache", self->uid);
+      g_hash_table_insert (event_cache, self->uid, self);
+    }
+
   e_cal_component_free_id (id);
   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_UID]);
 }