From 43556b800b7838fc989f243a2974d33a8f8a12ce Mon Sep 17 00:00:00 2001 From: Richard Mudgett Date: Wed, 9 Mar 2016 16:34:53 -0600 Subject: chan_sip.c: Fix reinviteid deadlock potential. This patch is part of a series to resolve deadlocks in chan_sip.c. Stopping a scheduled event can result in a deadlock if the scheduled event is running when you try to stop the event. If you hold a lock needed by the scheduled event while trying to stop the scheduled event then a deadlock can happen. The general strategy for resolving the deadlock potential is to push the actual starting and stopping of the scheduled events off onto the scheduler/do_monitor() thread by scheduling an immediate one shot scheduled event. Some restructuring may be needed because the code may assume that the start/stop of the scheduled events is immediate. ASTERISK-25023 Change-Id: I9c11b9d597468f63916c99e1dabff9f4a46f84c1 --- channels/chan_sip.c | 47 +++++++++++++++++++++++++++++++++++++---------- 1 file changed, 37 insertions(+), 10 deletions(-) (limited to 'channels/chan_sip.c') diff --git a/channels/chan_sip.c b/channels/chan_sip.c index c7cab1c93..f369df484 100644 --- a/channels/chan_sip.c +++ b/channels/chan_sip.c @@ -7041,21 +7041,44 @@ const char *hangup_cause2sip(int cause) return 0; } +/* Run by the sched thread. */ static int reinvite_timeout(const void *data) { struct sip_pvt *dialog = (struct sip_pvt *) data; - struct ast_channel *owner = sip_pvt_lock_full(dialog); + struct ast_channel *owner; + + owner = sip_pvt_lock_full(dialog); dialog->reinviteid = -1; check_pendings(dialog); if (owner) { ast_channel_unlock(owner); ast_channel_unref(owner); } - ao2_unlock(dialog); - dialog_unref(dialog, "unref for reinvite timeout"); + sip_pvt_unlock(dialog); + dialog_unref(dialog, "reinviteid complete"); + return 0; +} + +/* Run by the sched thread. */ +static int __stop_reinviteid(const void *data) +{ + struct sip_pvt *pvt = (void *) data; + + AST_SCHED_DEL_UNREF(sched, pvt->reinviteid, + dialog_unref(pvt, "Stop scheduled reinviteid")); + dialog_unref(pvt, "Stop reinviteid action"); return 0; } +static void stop_reinviteid(struct sip_pvt *pvt) +{ + dialog_ref(pvt, "Stop reinviteid action"); + if (ast_sched_add(sched, 0, __stop_reinviteid, pvt) < 0) { + /* Uh Oh. Expect bad behavior. */ + dialog_unref(pvt, "Failed to schedule stop reinviteid action"); + } +} + /*! \brief sip_hangup: Hangup SIP call * Part of PBX interface, called from ast_hangup */ static int sip_hangup(struct ast_channel *ast) @@ -7247,7 +7270,12 @@ static int sip_hangup(struct ast_channel *ast) * So, just in case, check for pending actions after a bit of time to trigger the pending * bye that we are setting above */ if (p->ongoing_reinvite && p->reinviteid < 0) { - p->reinviteid = ast_sched_add(sched, 32 * p->timer_t1, reinvite_timeout, dialog_ref(p, "ref for reinvite_timeout")); + p->reinviteid = ast_sched_add(sched, 32 * p->timer_t1, + reinvite_timeout, dialog_ref(p, "Schedule reinviteid")); + if (p->reinviteid < 0) { + /* Uh Oh. Expect bad behavior. */ + dialog_unref(p, "Failed to schedule reinviteid"); + } } } } @@ -22935,13 +22963,14 @@ static void check_pendings(struct sip_pvt *p) if (p->reinviteid > -1) { /* Outstanding p->reinviteid timeout, so wait... */ return; - } else if (p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA) { + } + if (p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA) { /* if we can't BYE, then this is really a pending CANCEL */ p->invitestate = INV_CANCELLED; transmit_request(p, SIP_CANCEL, p->lastinvite, XMIT_RELIABLE, FALSE); /* If the cancel occurred on an initial invite, cancel the pending BYE */ if (!ast_test_flag(&p->flags[1], SIP_PAGE2_DIALOG_ESTABLISHED)) { - ast_clear_flag(&p->flags[0], SIP_PENDINGBYE); + ast_clear_flag(&p->flags[0], SIP_PENDINGBYE | SIP_NEEDREINVITE); } /* Actually don't destroy us yet, wait for the 487 on our original INVITE, but do set an autodestruct just in case we never get it. */ @@ -22957,7 +22986,7 @@ static void check_pendings(struct sip_pvt *p) } /* Perhaps there is an SD change INVITE outstanding */ transmit_request_with_auth(p, SIP_BYE, 0, XMIT_RELIABLE, TRUE); - ast_clear_flag(&p->flags[0], SIP_PENDINGBYE); + ast_clear_flag(&p->flags[0], SIP_PENDINGBYE | SIP_NEEDREINVITE); } sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT); } else if (ast_test_flag(&p->flags[0], SIP_NEEDREINVITE)) { @@ -23249,9 +23278,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, const char *rest if ((resp >= 200 && reinvite)) { p->ongoing_reinvite = 0; - if (p->reinviteid > -1) { - AST_SCHED_DEL_UNREF(sched, p->reinviteid, dialog_unref(p, "unref dialog for reinvite timeout because of a final response")); - } + stop_reinviteid(p); } /* Final response, clear out pending invite */ -- cgit v1.2.3