XmppMessageBuikder::GetData() Fix potential data corruption

[Ananth Suryanarayana]

    In XmppMessageBuilder::GetData() don't return temporary stack variable address

    In XmppMessageBuilder::GetData(), address of a string allocated in stack as
    a temporary variable was returned to the caller in some case. This can cause
    memory corruption because the the temporary string will get destroyed right
    after it goes out of scope, in this case when we return to the caller from
    GetData().

diff --git a/src/bgp/xmpp_message_builder.cc b/src/bgp/xmpp_message_builder.cc
index 4258edc..9402dae 100644
--- a/src/bgp/xmpp_message_builder.cc
+++ b/src/bgp/xmpp_message_builder.cc
@@ -516,7 +516,7 @@ bool BgpXmppMessage::AddMvpnRoute(const BgpRoute *route,
 }

 const uint8_t *BgpXmppMessage::GetData(IPeerUpdate *peer, size_t *lenp,
- const string **msg_str) {
+ const string **msg_str, string *temp) {
     // Build begin line that contains message opening tag with from and to
     // attributes.
     msg_begin_.clear();
@@ -551,10 +551,10 @@ const uint8_t *BgpXmppMessage::GetData(IPeerUpdate *peer, size_t *lenp,
         *msg_str = &repr_;
         return reinterpret_cast<const uint8_t *>(repr_.c_str()) + extra;
     } else {
- string temp = msg_begin_ + string(repr_, kMaxFromToLength);
- *lenp = temp.size();
+ *temp = msg_begin_ + string(repr_, kMaxFromToLength);
+ *lenp = temp->size();
         *msg_str = NULL;
- return reinterpret_cast<const uint8_t *>(temp.c_str());
+ return reinterpret_cast<const uint8_t *>(temp->c_str());
     }
 }

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/41171
Submitter: Ananth Suryanarayana (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/41171
Committed: http://github.com/Juniper/contrail-controller/commit/c9e40b1c9076a4eccd8280aed1b814ca65b1f805
Submitter: Zuul v3 CI (<email address hidden>)
Branch: master

commit c9e40b1c9076a4eccd8280aed1b814ca65b1f805
Author: Ananth Suryanarayana <email address hidden>
Date: Wed Mar 28 02:31:30 2018 -0700

In XmppMessageBuilder::GetData() don't return temporary stack variable address

In XmppMessageBuilder::GetData(), address of a string allocated in stack as
a temporary variable was returned to the caller in some case. This can cause
memory corruption because the the temporary string will get destroyed right
after it goes out of scope, in this case when we return to the caller from
GetData().

Fixed by ensuring that caller of GetData() provides the necessary temporary
storage space for the "temp" std::string

Change-Id: I27e622a34b72717cad90dc9553936182c2a77c6a
Closes-Bug: 1759744