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res_pjsip_session.c: Fix crash when declining an active stream.

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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
This commit is contained in:
Richard Mudgett
2017-08-18 17:37:12 -05:00
parent 17976d1b4e
commit f2c14f00b8
1 changed files with 32 additions and 6 deletions
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38
res/res_pjsip_session.c
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@@ -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);
}