ast_framehook_attach() must be called with the channel locked.

The framehook container could become corrupted if the channel lock is not
held before calling.

Change-Id: I1a6b957a1f7b899eb29a186915f8cccab886a438

main/bridge_basic.c

@@ -3090,7 +3090,9 @@ static int attach_framehook(struct attended_transfer_properties *props, struct a
 	ao2_ref(props, +1);
 	target_interface.data = props;
 
+	ast_channel_lock(channel);
 	props->target_framehook_id = ast_framehook_attach(channel, &target_interface);
+	ast_channel_unlock(channel);
 	if (props->target_framehook_id == -1) {
 		ao2_ref(props, -1);
 		return -1;

res/res_pjsip_refer.c

@@ -607,7 +607,10 @@ static void refer_blind_callback(struct ast_channel *chan, struct transfer_chann
 		ao2_ref(refer->progress, +1);
 
 		/* If we can't attach a frame hook for whatever reason send a notification of success immediately */
-		if ((refer->progress->framehook = ast_framehook_attach(chan, &hook)) < 0) {
+		ast_channel_lock(chan);
+		refer->progress->framehook = ast_framehook_attach(chan, &hook);
+		ast_channel_unlock(chan);
+		if (refer->progress->framehook < 0) {
 			struct refer_progress_notification *notification = refer_progress_notification_alloc(refer->progress, 200,
 				PJSIP_EVSUB_STATE_TERMINATED);
 

res/res_pjsip_t38.c

@@ -501,25 +501,27 @@ static void t38_attach_framehook(struct ast_sip_session *session)
 		return;
 	}
 
-	/* Skip attaching the framehook if the T.38 datastore already exists for the channel */
 	ast_channel_lock(session->channel);
-	if ((datastore = ast_channel_datastore_find(session->channel, &t38_framehook_datastore, NULL))) {
+
+	/* Skip attaching the framehook if the T.38 datastore already exists for the channel */
+	datastore = ast_channel_datastore_find(session->channel, &t38_framehook_datastore,
+		NULL);
+	if (datastore) {
 		ast_channel_unlock(session->channel);
 		return;
 	}
-	ast_channel_unlock(session->channel);
 
 	framehook_id = ast_framehook_attach(session->channel, &hook);
 	if (framehook_id < 0) {
-		ast_log(LOG_WARNING, "Could not attach T.38 Frame hook to channel, T.38 will be unavailable on '%s'\n",
+		ast_log(LOG_WARNING, "Could not attach T.38 Frame hook, T.38 will be unavailable on '%s'\n",
 			ast_channel_name(session->channel));
+		ast_channel_unlock(session->channel);
 		return;
 	}
 
-	ast_channel_lock(session->channel);
 	datastore = ast_datastore_alloc(&t38_framehook_datastore, NULL);
 	if (!datastore) {
-		ast_log(LOG_ERROR, "Could not attach T.38 Frame hook to channel, T.38 will be unavailable on '%s'\n",
+		ast_log(LOG_ERROR, "Could not alloc T.38 Frame hook datastore, T.38 will be unavailable on '%s'\n",
 			ast_channel_name(session->channel));
 		ast_framehook_detach(session->channel, framehook_id);
 		ast_channel_unlock(session->channel);