From f2c14f00b8ae4cd1fa809db705d4c368f1cfed1a Mon Sep 17 00:00:00 2001
From: Richard Mudgett <rmudgett@digium.com>
Date: Fri, 18 Aug 2017 17:37:12 -0500
Subject: [PATCH] res_pjsip_session.c: Fix crash when declining an active
stream.
If a previously active stream is declined we could crash because the
channel's thread is still using the stream while we are updating the
topology in the serializer thread.
* Defer removing any declined stream's handler until we have blocked the
channel's thread with the channel lock.
ASTERISK-27212
Change-Id: I50e1d3ef26f8e41948f4c411ee329aa3b960a420
---
res/res_pjsip_session.c | 38 ++++++++++++++++++++++++++++++++------
1 file changed, 32 insertions(+), 6 deletions(-)
diff --git a/res/res_pjsip_session.c b/res/res_pjsip_session.c
index c4b0041a12..b6b8a21ac3 100644
--- a/res/res_pjsip_session.c
+++ b/res/res_pjsip_session.c
@@ -784,12 +784,11 @@ static int handle_negotiated_sdp(struct ast_sip_session *session, const pjmedia_
* we remove it as a result of the stream limit being reached.
*/
if (ast_stream_get_state(stream) == AST_STREAM_STATE_REMOVED) {
- /* This stream is no longer being used so release any resources the handler
- * may have on it.
+ /*
+ * Defer removing the handler until we are ready to activate
+ * the new topology. The channel's thread may still be using
+ * the stream and we could crash before we are ready.
*/
- if (session_media->handler) {
- session_media_set_handler(session_media, NULL);
- }
continue;
}
@@ -801,6 +800,32 @@ static int handle_negotiated_sdp(struct ast_sip_session *session, const pjmedia_
/* Apply the pending media state to the channel and make it active */
ast_channel_lock(session->channel);
+ /* Now update the stream handler for any declined/removed streams */
+ for (i = 0; i < local->media_count; ++i) {
+ struct ast_sip_session_media *session_media;
+ struct ast_stream *stream;
+
+ if (!remote->media[i]) {
+ continue;
+ }
+
+ ast_assert(i < AST_VECTOR_SIZE(&session->pending_media_state->sessions));
+ ast_assert(i < ast_stream_topology_get_count(session->pending_media_state->topology));
+
+ session_media = AST_VECTOR_GET(&session->pending_media_state->sessions, i);
+ stream = ast_stream_topology_get_stream(session->pending_media_state->topology, i);
+
+ if (ast_stream_get_state(stream) == AST_STREAM_STATE_REMOVED
+ && session_media->handler) {
+ /*
+ * This stream is no longer being used and the channel's thread
+ * is held off because we have the channel lock so release any
+ * resources the handler may have on it.
+ */
+ session_media_set_handler(session_media, NULL);
+ }
+ }
+
/* Update the topology on the channel to match the accepted one */
topology = ast_stream_topology_clone(session->pending_media_state->topology);
if (topology) {
@@ -814,8 +839,9 @@ static int handle_negotiated_sdp(struct ast_sip_session *session, const pjmedia_
/* Add all the file descriptors from the pending media state */
for (i = 0; i < AST_VECTOR_SIZE(&session->pending_media_state->read_callbacks); ++i) {
- struct ast_sip_session_media_read_callback_state *callback_state = AST_VECTOR_GET_ADDR(&session->pending_media_state->read_callbacks, i);
+ struct ast_sip_session_media_read_callback_state *callback_state;
+ callback_state = AST_VECTOR_GET_ADDR(&session->pending_media_state->read_callbacks, i);
ast_channel_internal_fd_set(session->channel, i + AST_EXTENDED_FDS, callback_state->fd);
}
--
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