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AST-2019-004 - res_pjsip_t38.c: Add NULL checks before using session media 

After receiving a 200 OK with a declined stream in response to a T.38
initiated re-invite Asterisk would crash when attempting to dereference
a NULL session media object.

This patch checks to make sure the session media object is not NULL before
attempting to use it.

ASTERISK-28495
patches:
  ast-2019-004.patch submitted by Alexei Gradinari (license 5691)

Change-Id: I168f45f4da29cfe739acf87e597baa2aae7aa572
This commit is contained in:
Kevin Harwell 2019-08-20 15:05:45 -05:00 committed by Gerrit
parent 260969f5ad
commit 965df3c228
1 changed files with 45 additions and 27 deletions
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72
res/res_pjsip_t38.c
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@ -203,7 +203,6 @@ static int t38_automatic_reject(void *obj)
{
RAII_VAR(struct ast_sip_session *, session, obj, ao2_cleanup);
RAII_VAR(struct ast_datastore *, datastore, ast_sip_session_get_datastore(session, "t38"), ao2_cleanup);
struct ast_sip_session_media *session_media;
if (!datastore) {
return 0;
@ -212,8 +211,7 @@ static int t38_automatic_reject(void *obj)
ast_debug(2, "Automatically rejecting T.38 request on channel '%s'\n",
session->channel ? ast_channel_name(session->channel) : "<gone>");
session_media = session->pending_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(session, session_media, datastore->data, T38_REJECTED);
t38_change_state(session, NULL, datastore->data, T38_REJECTED);
ast_sip_session_resume_reinvite(session);
return 0;
@ -322,28 +320,37 @@ static int t38_reinvite_response_cb(struct ast_sip_session *session, pjsip_rx_da
int index;
session_media = session->active_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(session, session_media, state, T38_ENABLED);
if (!session_media) {
ast_log(LOG_WARNING, "Received %d response to T.38 re-invite on '%s' but no active session media\n",
status.code, session->channel ? ast_channel_name(session->channel) : "unknown channel");
} else {
t38_change_state(session, session_media, state, T38_ENABLED);
/* Stop all the streams in the stored away active state, they'll go back to being active once
* we reinvite back.
*/
for (index = 0; index < AST_VECTOR_SIZE(&state->media_state->sessions); ++index) {
struct ast_sip_session_media *session_media = AST_VECTOR_GET(&state->media_state->sessions, index);
/* Stop all the streams in the stored away active state, they'll go back to being active once
* we reinvite back.
*/
for (index = 0; index < AST_VECTOR_SIZE(&state->media_state->sessions); ++index) {
struct ast_sip_session_media *session_media = AST_VECTOR_GET(&state->media_state->sessions, index);
if (session_media && session_media->handler && session_media->handler->stream_stop) {
session_media->handler->stream_stop(session_media);
if (session_media && session_media->handler && session_media->handler->stream_stop) {
session_media->handler->stream_stop(session_media);
}
}
return 0;
}
} else {
session_media = session->pending_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(session, session_media, state, T38_REJECTED);
/* Abort this attempt at switching to T.38 by resetting the pending state and freeing our stored away active state */
ast_sip_session_media_state_free(state->media_state);
state->media_state = NULL;
ast_sip_session_media_state_reset(session->pending_media_state);
}
/* If no session_media then response contained a declined stream, so disable */
t38_change_state(session, NULL, state, session_media ? T38_REJECTED : T38_DISABLED);
/* Abort this attempt at switching to T.38 by resetting the pending state and freeing our stored away active state */
ast_sip_session_media_state_free(state->media_state);
state->media_state = NULL;
ast_sip_session_media_state_reset(session->pending_media_state);
return 0;
}
@ -426,12 +433,10 @@ static int t38_interpret_parameters(void *obj)
/* Negotiation can not take place without a valid max_ifp value. */
if (!parameters->max_ifp) {
if (data->session->t38state == T38_PEER_REINVITE) {
session_media = data->session->pending_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(data->session, session_media, state, T38_REJECTED);
t38_change_state(data->session, NULL, state, T38_REJECTED);
ast_sip_session_resume_reinvite(data->session);
} else if (data->session->t38state == T38_ENABLED) {
session_media = data->session->active_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(data->session, session_media, state, T38_DISABLED);
t38_change_state(data->session, NULL, state, T38_DISABLED);
ast_sip_session_refresh(data->session, NULL, NULL, NULL,
AST_SIP_SESSION_REFRESH_METHOD_INVITE, 1, state->media_state);
state->media_state = NULL;
@ -454,6 +459,11 @@ static int t38_interpret_parameters(void *obj)
state->our_parms.version = MIN(state->our_parms.version, state->their_parms.version);
state->our_parms.rate_management = state->their_parms.rate_management;
session_media = data->session->pending_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
if (!session_media) {
ast_log(LOG_ERROR, "Failed to negotiate parameters for reinvite on channel '%s' (No pending session media).\n",
data->session->channel ? ast_channel_name(data->session->channel) : "unknown channel");
break;
}
ast_udptl_set_local_max_ifp(session_media->udptl, state->our_parms.max_ifp);
t38_change_state(data->session, session_media, state, T38_ENABLED);
ast_sip_session_resume_reinvite(data->session);
@ -468,8 +478,13 @@ static int t38_interpret_parameters(void *obj)
}
state->our_parms = *parameters;
session_media = media_state->default_session[AST_MEDIA_TYPE_IMAGE];
if (!session_media) {
ast_log(LOG_ERROR, "Failed to negotiate parameters on channel '%s' (No default session media).\n",
data->session->channel ? ast_channel_name(data->session->channel) : "unknown channel");
break;
}
ast_udptl_set_local_max_ifp(session_media->udptl, state->our_parms.max_ifp);
t38_change_state(data->session, session_media, state, T38_LOCAL_REINVITE);
t38_change_state(data->session, NULL, state, T38_LOCAL_REINVITE);
ast_sip_session_refresh(data->session, NULL, t38_reinvite_sdp_cb, t38_reinvite_response_cb,
AST_SIP_SESSION_REFRESH_METHOD_INVITE, 1, media_state);
}
@ -478,12 +493,10 @@ static int t38_interpret_parameters(void *obj)
case AST_T38_REFUSED:
case AST_T38_REQUEST_TERMINATE: /* Shutdown T38 */
if (data->session->t38state == T38_PEER_REINVITE) {
session_media = data->session->pending_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(data->session, session_media, state, T38_REJECTED);
t38_change_state(data->session, NULL, state, T38_REJECTED);
ast_sip_session_resume_reinvite(data->session);
} else if (data->session->t38state == T38_ENABLED) {
session_media = data->session->active_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
t38_change_state(data->session, session_media, state, T38_DISABLED);
t38_change_state(data->session, NULL, state, T38_DISABLED);
ast_sip_session_refresh(data->session, NULL, NULL, NULL, AST_SIP_SESSION_REFRESH_METHOD_INVITE, 1, state->media_state);
state->media_state = NULL;
}
@ -493,6 +506,11 @@ static int t38_interpret_parameters(void *obj)
if (data->session->t38state == T38_PEER_REINVITE) {
session_media = data->session->pending_media_state->default_session[AST_MEDIA_TYPE_IMAGE];
if (!session_media) {
ast_log(LOG_ERROR, "Failed to request parameters for reinvite on channel '%s' (No pending session media).\n",
data->session->channel ? ast_channel_name(data->session->channel) : "unknown channel");
break;
}
parameters.max_ifp = ast_udptl_get_far_max_ifp(session_media->udptl);
parameters.request_response = AST_T38_REQUEST_NEGOTIATE;
ast_queue_control_data(data->session->channel, AST_CONTROL_T38_PARAMETERS, &parameters, sizeof(parameters));
@ -788,7 +806,7 @@ static int negotiate_incoming_sdp_stream(struct ast_sip_session *session,
if ((session->t38state == T38_REJECTED) || (session->t38state == T38_DISABLED)) {
ast_debug(3, "Declining; T.38 state is rejected or declined\n");
t38_change_state(session, session_media, state, T38_DISABLED);
t38_change_state(session, NULL, state, T38_DISABLED);
return 0;
}