D-Bus server: use weak pointers with asynchronous D-Bus calls

An asynchronous D-Bus call will invoke the callback even if
the call instance itself was already deleted. Therefore binding
the this pointer of the call instance owner is not safe. This
caused use-after-free errors in local sync (found during testing).

Use weak pointers as a precaution where it can be done easily.
Some remaining start() calls still need to be converted.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/dbus/server/session.cpp b/src/dbus/server/session.cpp
index f8de03a1..157f153e 100644
--- a/src/dbus/server/session.cpp
+++ b/src/dbus/server/session.cpp
@@ -28,6 +28,7 @@
 
 #include <syncevo/ForkExec.h>
 #include <syncevo/SyncContext.h>
+#include <syncevo/BoostHelper.h>
 
 #include <memory>
 
@@ -408,7 +409,7 @@ void Session::sync2(const std::string &mode, const SessionCommon::SourceModes_t
     // the error is recorded before ending the session. Premature
     // exits by the helper are handled by D-Bus, which then will abort
     // the pending method call.
-    m_helper->m_sync.start(params, boost::bind(&Session::dbusResultCb, this, "sync()", _1, _2));
+    m_helper->m_sync.start(params, boost::bind(&Session::dbusResultCb, m_me, "sync()", _1, _2));
 }
 
 void Session::abort()
@@ -1193,7 +1194,7 @@ void Session::restore2(const string &dir, bool before, const std::vector<std::st
 
     // helper is ready, tell it what to do
     m_helper->m_restore.start(m_configName, dir, before, sources,
-                              boost::bind(&Session::dbusResultCb, this, "restore()", _1, _2));
+                              boost::bind(&Session::dbusResultCb, m_me, "restore()", _1, _2));
 }
 
 void Session::execute(const vector<string> &args, const map<string, string> &vars)
@@ -1224,7 +1225,7 @@ void Session::execute2(const vector<string> &args, const map<string, string> &va
 
     // helper is ready, tell it what to do
     m_helper->m_execute.start(args, vars,
-                              boost::bind(&Session::dbusResultCb, this, "execute()", _1, _2));
+                              boost::bind(&Session::dbusResultCb, m_me, "execute()", _1, _2));
 }
 
 /*Implementation of Session.CheckPresence */