stasis: Fix "FRACK!, Failed assertion bad magic number" when unsubscribing

When unsubscribing from an endpoint technology a FRACK
would occur due to incorrect reference counting. This fixes
that issue, along with some other issues.

Fixed a typo in get_subscription when calling ao2_find as it
needed to pass the endpoint ID and not the entire object.

Fixed scenario where a subscription would get returned when
it shouldn't have been when searching based on endpoint
technology.

A doulbe unreference has also been resolved by only explicitly
releasing the reference held by tech_subscriptions.

ASTERISK-28237 #close
Reported by: Lucas Tardioli Silveira

Change-Id: Ia91b15f8e5ea68f850c66889a6325d9575901729

diff --git a/res/stasis/messaging.c b/res/stasis/messaging.c
index 2caa8ed228db6438fbccdf5eaffa6a2ccedd60a0..e1d54c4a79e60a82dbbea8ca471c524717b9b377 100644 (file)
--- a/res/stasis/messaging.c
+++ b/res/stasis/messaging.c
@@ -396,7 +396,7 @@ static struct message_subscription *get_subscription(struct ast_endpoint *endpoi
        struct message_subscription *sub = NULL;
 
        if (endpoint && !ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
-               sub = ao2_find(endpoint_subscriptions, endpoint, OBJ_SEARCH_KEY);
+               sub = ao2_find(endpoint_subscriptions, ast_endpoint_get_id(endpoint), OBJ_SEARCH_KEY);
        } else {
                int i;
 
@@ -408,6 +408,11 @@ static struct message_subscription *get_subscription(struct ast_endpoint *endpoi
                                ao2_bump(sub);
                                break;
                        }
+
+                       /* Need to reset the pointer at this line to prevent from using the wrong subscription due to
+                        * the token check failing.
+                        */
+                       sub = NULL;
                }
                ast_rwlock_unlock(&tech_subscriptions_lock);
        }
@@ -441,10 +446,10 @@ void messaging_app_unsubscribe_endpoint(const char *app_name, const char *endpoi
                        AST_VECTOR_REMOVE_CMP_UNORDERED(&tech_subscriptions, endpoint ? ast_endpoint_get_id(endpoint) : TECH_WILDCARD,
                                messaging_subscription_cmp, AST_VECTOR_ELEM_CLEANUP_NOOP);
                        ast_rwlock_unlock(&tech_subscriptions_lock);
+                       ao2_ref(sub, -1); /* Release the reference held by tech_subscriptions */
                }
        }
        ao2_unlock(sub);
-       ao2_ref(sub, -1);
 
        ast_debug(3, "App '%s' unsubscribed to messages from endpoint '%s'\n", app_name, endpoint ? ast_endpoint_get_id(endpoint) : "-- ALL --");
        ast_test_suite_event_notify("StasisMessagingSubscription", "SubState: Unsubscribed\r\nAppName: %s\r\nToken: %s\r\n",
@@ -464,6 +469,11 @@ static struct message_subscription *get_or_create_subscription(struct ast_endpoi
                return NULL;
        }
 
+       /* Either endpoint_subscriptions or tech_subscriptions will hold a reference to
+        * the subscription. This reference is released to allow the subscription to
+        * eventually destruct when there are no longer any applications receiving
+        * events from the subscription.
+        */
        if (endpoint && !ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
                ao2_link(endpoint_subscriptions, sub);
        } else {