From 9cd8a1df792c26cc4e82263a950f877d4c255100 Mon Sep 17 00:00:00 2001
From: Richard Mudgett <rmudgett@digium.com>
Date: Wed, 5 Jul 2017 13:39:45 -0500
Subject: [PATCH] res_rtp_asterisk.c: Fix TURN deadlock by using ICE session
group lock.
When a message is received on the TURN socket, the code processing the
message needs to call into the ICE/STUN session for further processing.
This code path locks the TURN group lock then the ICE/STUN group lock. In
another thread an ICE/STUN timer can fire off to send a keep alive message
over the TURN socket. In this code path, the ICE/STUN group lock is
obtained then the TURN group lock is obtained to send the packet. A
classic deadlock case if the group locks are not the same.
* Made TURN get created using the ICE/STUN session's group lock.
NOTE: I was originally concerned that the ICE/STUN session can get
recreated by ice_reset_session() for an event like RTCP multiplexing
causing a change during SDP negotiation. In this case the TURN group lock
would become different. However, TURN is also recreated as part of the
ICE/STUN recreation in ice_create() when all known ICE candidates are
added to the new ICE session. While the ICE/STUN and TURN sessions are
being recreated there is a period where the group locks could be
different.
ASTERISK-27023 #close
Patches:
res_rtp_asterisk-turn-deadlock-fix.patch (license #6502)
patch uploaded by Michael Walton (modified)
Change-Id: Ic870edb99ce4988a8c8eb6e678ca7f19da1432b9
---
res/res_rtp_asterisk.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/res/res_rtp_asterisk.c b/res/res_rtp_asterisk.c
index 01dfe76f29..e60d4af757 100644
--- a/res/res_rtp_asterisk.c
+++ b/res/res_rtp_asterisk.c
@@ -1293,6 +1293,8 @@ static void ast_rtp_ice_turn_request(struct ast_rtp_instance *instance, enum ast
pj_turn_session_info info;
struct ast_sockaddr local, loop;
pj_status_t status;
+ pj_turn_sock_cfg turn_sock_cfg;
+ struct ice_wrap *ice;
ast_rtp_instance_get_local_address(instance, &local);
if (ast_sockaddr_is_ipv4(&local)) {
@@ -1355,11 +1357,20 @@ static void ast_rtp_ice_turn_request(struct ast_rtp_instance *instance, enum ast
pj_stun_config_init(&stun_config, &cachingpool.factory, 0, rtp->ioqueue->ioqueue, rtp->ioqueue->timerheap);
+ /* Use ICE session group lock for TURN session to avoid deadlock */
+ pj_turn_sock_cfg_default(&turn_sock_cfg);
+ ice = rtp->ice;
+ if (ice) {
+ turn_sock_cfg.grp_lock = ice->real_ice->grp_lock;
+ ao2_ref(ice, +1);
+ }
+
/* Release the instance lock to avoid deadlock with PJPROJECT group lock */
ao2_unlock(instance);
status = pj_turn_sock_create(&stun_config,
ast_sockaddr_is_ipv4(&addr) ? pj_AF_INET() : pj_AF_INET6(), conn_type,
- turn_cb, NULL, instance, turn_sock);
+ turn_cb, &turn_sock_cfg, instance, turn_sock);
+ ao2_cleanup(ice);
if (status != PJ_SUCCESS) {
ast_log(LOG_WARNING, "Could not create a TURN client socket\n");
ao2_lock(instance);
--
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