Fix bug in InitParseWithoutQuestion

net/dns/dns_response.cc

Index: net/dns/dns_response.cc
diff --git a/net/dns/dns_response.cc b/net/dns/dns_response.cc
index 4a3371c2adb1b42b267f7a1c161ca58f191f94f4..38f93c10659d07879467ff9dec0515667e0a63dc 100644
--- a/net/dns/dns_response.cc
+++ b/net/dns/dns_response.cc
@@ -162,6 +162,7 @@ DnsResponse::~DnsResponse() {
 }
 
 bool DnsResponse::InitParse(int nbytes, const DnsQuery& query) {
+  DCHECK_GE(nbytes, 0);
   // Response includes query, it should be at least that size.
   if (nbytes < query.io_buffer()->size() || nbytes >= io_buffer_->size())
     return false;
@@ -190,10 +191,13 @@ bool DnsResponse::InitParse(int nbytes, const DnsQuery& query) {
 }
 
 bool DnsResponse::InitParseWithoutQuery(int nbytes) {
-  if (nbytes >= io_buffer_->size())
-    return false;
+  DCHECK_GE(nbytes, 0);
 
   size_t hdr_size = sizeof(dns_protocol::Header);
+
+  if (nbytes < static_cast<int>(hdr_size) || nbytes >= io_buffer_->size())
+    return false;
+
   parser_ = DnsRecordParser(
       io_buffer_->data(), nbytes, hdr_size);