From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Tue, 5 Jun 2018 22:10:13 +0000 (+0200)
Subject: dnsdist: Don't access the TCP buffer vector past its size
X-Git-Tag: dnsdist-1.3.1~40^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=60a518c8c246f43c53694160ebb7ca8b8b5c6346;p=pdns

dnsdist: Don't access the TCP buffer vector past its size

The required memory has been reserve()'d, but we are not allowed to
access it directly, and it breaks when compiled with the following
flag, checking any access to containers as if .at() were used:

-D_GLIBCXX_ASSERTIONS
---

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index 0eb7ea139..ab2bda916 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -315,7 +315,7 @@ void* tcpClientThread(int pipefd)
         bool ecsAdded = false;
         /* allocate a bit more memory to be able to spoof the content,
            or to add ECS without allocating a new buffer */
-        queryBuffer.reserve(qlen + 512);
+        queryBuffer.resize(qlen + 512);
 
         char* query = &queryBuffer[0];
         handler.read(query, qlen, g_tcpRecvTimeout, remainingTime);
@@ -358,7 +358,7 @@ void* tcpClientThread(int pipefd)
 	uint16_t qtype, qclass;
 	unsigned int consumed = 0;
 	DNSName qname(query, qlen, sizeof(dnsheader), false, &qtype, &qclass, &consumed);
-	DNSQuestion dq(&qname, qtype, qclass, &dest, &ci.remote, dh, queryBuffer.capacity(), qlen, true, &queryRealTime);
+	DNSQuestion dq(&qname, qtype, qclass, &dest, &ci.remote, dh, queryBuffer.size(), qlen, true, &queryRealTime);
 
 	if (!processQuery(holders, dq, poolname, &delayMsec, now)) {
 	  goto drop;