From 7a5f6684f05e03c51b5d004156dba9df2711dd50 Mon Sep 17 00:00:00 2001
From: Richard Mudgett <rmudgett@digium.com>
Date: Mon, 7 Nov 2011 19:54:09 +0000
Subject: [PATCH] Fix deadlock if peer is destroyed while sending MWI notice.
A dialog cannot be destroyed by the ao2_callback dialog_needdestroy
because of a deadlock between the dialogs container lock and the RWLOCK of
the events subscription list.
* Create dialogs_to_destroy container to hold dialogs that will be
destroyed.
* Ensure that the event subscription callback will never happen with an
invalid peer pointer by making the event callback removal the first thing
in the peer destructor callback.
NOTE: This particular deadlock will not happen with Asterisk 10, but some
of the changes still apply.
(closes issue ASTERISK-18747)
Reported by: Gregory Hinton Nietsky
Review: https://reviewboard.asterisk.org/r/1564/
........
Merged revisions 343577 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........
Merged revisions 343578 from http://svn.asterisk.org/svn/asterisk/branches/10
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@343579 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
channels/chan_sip.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index e7b678b9cd..c55052385d 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -2956,6 +2956,13 @@ static void *dialog_unlink_rtpcheck(struct sip_pvt *dialog)
return NULL;
}
+/*!
+ * \brief Unlink a dialog from the dialogs container, as well as any other places
+ * that it may be currently stored.
+ *
+ * \note A reference to the dialog must be held before calling this function, and this
+ * function does not release that reference.
+ */
void dialog_unlink_all(struct sip_pvt *dialog)
{
struct sip_pkt *cp;
@@ -4589,9 +4596,18 @@ static void sip_destroy_peer_fn(void *peer)
static void sip_destroy_peer(struct sip_peer *peer)
{
ast_debug(3, "Destroying SIP peer %s\n", peer->name);
- if (peer->outboundproxy)
+
+ /*
+ * Remove any mailbox event subscriptions for this peer before
+ * we destroy anything. An event subscription callback may be
+ * happening right now.
+ */
+ clear_peer_mailboxes(peer);
+
+ if (peer->outboundproxy) {
ao2_ref(peer->outboundproxy, -1);
- peer->outboundproxy = NULL;
+ peer->outboundproxy = NULL;
+ }
/* Delete it, it needs to disappear */
if (peer->call) {
@@ -4625,7 +4641,6 @@ static void sip_destroy_peer(struct sip_peer *peer)
}
if (peer->dnsmgr)
ast_dnsmgr_release(peer->dnsmgr);
- clear_peer_mailboxes(peer);
if (peer->socket.tcptls_session) {
ao2_ref(peer->socket.tcptls_session, -1);
@@ -17045,14 +17060,12 @@ static int dialog_checkrtp_cb(void *dialogobj, void *arg, int flags)
* \brief Match dialogs that need to be destroyed
*
* \details This is used with ao2_callback to unlink/delete all dialogs that
- * are marked needdestroy. It will return CMP_MATCH for candidates, and they
- * will be unlinked.
+ * are marked needdestroy.
*
* \todo Re-work this to improve efficiency. Currently, this function is called
* on _every_ dialog after processing _every_ incoming SIP/UDP packet, or
* potentially even more often when the scheduler has entries to run.
*/
-
static int dialog_needdestroy(void *dialogobj, void *arg, int flags)
{
struct sip_pvt *dialog = dialogobj;
--
GitLab