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CHANNEL(peer), chan_iax2, res_fax, SNMP agent: Fix deadlock from reaching across a bridge.

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Calling ast_channel_bridge_peer() cannot be done while holding any channel
locks.  The reported issue hit the deadlock in chan_iax2, but an audit of
the ast_channel_bridge_peer() calls found three more locations where the
same deadlock can occur.

* Made CHANNEL(peer), res_fax, and the SNMP agent not call
ast_channel_bridge_peer() with any channel locked.  For CHANNEL(peer) I
had to rework the logic to not hold the channel lock.

* Made chan_iax2 no longer call ast_channel_bridge_peer().  It was done
for legacy reasons that no longer apply.

* Removed the iax.conf forcejitterbuffer option.  It is now always enabled
when the jitterbuffer option is enabled.  If you put a jitter buffer on a
channel it will be on the channel.

ASTERISK-24600 #close
Reported by: Jeff Collell

Review: https://reviewboard.asterisk.org/r/4342/


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@430817 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Richard Mudgett
2015-01-20 16:46:16 +00:00
parent 072db5e1b9
commit 6af6a216a1
6 changed files with 52 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
res/res_fax.c
View File

@@ -2888,6 +2888,7 @@ static struct fax_gateway *fax_gateway_new(struct ast_channel *chan, struct ast_
static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session_details *details, struct ast_channel *chan)
{
struct ast_fax_session *s;
int start_res;
/* create the FAX session */
if (!(s = fax_session_new(details, chan, gateway->s, gateway->token))) {
@@ -2908,7 +2909,10 @@ static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session
gateway->s = s;
gateway->token = NULL;
if (gateway->s->tech->start_session(gateway->s) < 0) {
ast_channel_unlock(chan);
start_res = gateway->s->tech->start_session(gateway->s);
ast_channel_lock(chan);
if (start_res < 0) {
ast_string_field_set(details, result, "FAILED");
ast_string_field_set(details, resultstr, "error starting gateway session");
ast_string_field_set(details, error, "INIT_ERROR");

10
res/snmp/agent.c
View File

@@ -298,12 +298,18 @@ static u_char *ast_var_channels_table(struct variable *vp, oid *name, size_t *le
}
break;
case ASTCHANBRIDGE:
if ((bridge = ast_channel_bridge_peer(chan)) != NULL) {
ast_channel_unlock(chan);
bridge = ast_channel_bridge_peer(chan);
if (bridge) {
ast_channel_lock(bridge);
ast_copy_string(string_ret, ast_channel_name(bridge), sizeof(string_ret));
ast_channel_unlock(bridge);
ast_channel_unref(bridge);
*var_len = strlen(string_ret);
ret = (u_char *)string_ret;
ast_channel_unref(bridge);
}
ast_channel_lock(chan);
break;
case ASTCHANMASQ:
if (ast_channel_masq(chan) && !ast_strlen_zero(ast_channel_name(ast_channel_masq(chan)))) {