From 6d4897776571022c8c5609ec909d44739d399586 Mon Sep 17 00:00:00 2001
From: Bill Stoffel <bstoffel@belvederetrading.com>
Date: Wed, 17 Feb 2021 15:28:11 -0600
Subject: [PATCH] Lock subscription mutex around optional trace logs

- The _subscribers vector was utilized in the trace function without
  obtaining a lock.  This vector could change size and lead to a segfault.
---
 cpp/src/IceStorm/TopicI.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/cpp/src/IceStorm/TopicI.cpp b/cpp/src/IceStorm/TopicI.cpp
index 480189c6387..122fa29b919 100644
--- a/cpp/src/IceStorm/TopicI.cpp
+++ b/cpp/src/IceStorm/TopicI.cpp
@@ -503,6 +503,8 @@ TopicImpl::subscribeAndGetPublisher(const QoS& qos, const Ice::ObjectPrx& obj)
     Ice::Identity id = obj->ice_getIdentity();
 
     TraceLevelsPtr traceLevels = _instance->traceLevels();
+
+    IceUtil::Mutex::Lock sync(_subscribersMutex);
     if(traceLevels->topic > 0)
     {
         Ice::Trace out(traceLevels->logger, traceLevels->topicCat);
@@ -525,8 +527,6 @@ TopicImpl::subscribeAndGetPublisher(const QoS& qos, const Ice::ObjectPrx& obj)
         }
     }
 
-    IceUtil::Mutex::Lock sync(_subscribersMutex);
-
     SubscriberRecord record;
     record.id = id;
     record.obj = obj;
@@ -587,6 +587,7 @@ TopicImpl::unsubscribe(const Ice::ObjectPrx& subscriber)
 
     Ice::Identity id = subscriber->ice_getIdentity();
 
+    IceUtil::Mutex::Lock sync(_subscribersMutex);
     if(traceLevels->topic > 0)
     {
         Ice::Trace out(traceLevels->logger, traceLevels->topicCat);
@@ -598,8 +599,6 @@ TopicImpl::unsubscribe(const Ice::ObjectPrx& subscriber)
             trace(out, _instance, _subscribers);
         }
     }
-
-    IceUtil::Mutex::Lock sync(_subscribersMutex);
     Ice::IdentitySeq ids;
     ids.push_back(id);
     removeSubscribers(ids);