Blame SOURCES/dnsmasq-2.76-underflow.patch

e87dd3
From d4f2e0b8d8f0b5daa0d468f62a0d5f1df58ac325 Mon Sep 17 00:00:00 2001
e87dd3
From: Doran Moppert <dmoppert@redhat.com>
e87dd3
Date: Tue, 26 Sep 2017 14:48:20 +0930
e87dd3
Subject: [PATCH 9/9]     google patch hand-applied
e87dd3
e87dd3
---
e87dd3
 src/edns0.c   | 10 +++++-----
e87dd3
 src/forward.c |  4 ++++
e87dd3
 src/rfc1035.c |  6 ++++--
e87dd3
 3 files changed, 13 insertions(+), 7 deletions(-)
e87dd3
e87dd3
diff --git a/src/edns0.c b/src/edns0.c
e87dd3
index 0552d38..bec4a36 100644
e87dd3
--- a/src/edns0.c
e87dd3
+++ b/src/edns0.c
e87dd3
@@ -212,11 +212,11 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
e87dd3
       /* Copy back any options */
e87dd3
       if (buff)
e87dd3
 	{
e87dd3
-          if (p + rdlen > limit)
e87dd3
-          {
e87dd3
-            free(buff);
e87dd3
-            return plen; /* Too big */
e87dd3
-          }
e87dd3
+	  if (p + rdlen > limit)
e87dd3
+	  {
e87dd3
+	    free(buff);
e87dd3
+	    return plen; /* Too big */
e87dd3
+	  }
e87dd3
 	  memcpy(p, buff, rdlen);
e87dd3
 	  free(buff);
e87dd3
 	  p += rdlen;
e87dd3
diff --git a/src/forward.c b/src/forward.c
e87dd3
index 0f8f462..a729c06 100644
e87dd3
--- a/src/forward.c
e87dd3
+++ b/src/forward.c
e87dd3
@@ -1412,6 +1412,10 @@ void receive_query(struct listener *listen, time_t now)
e87dd3
 	udp_size = PACKETSZ; /* Sanity check - can't reduce below default. RFC 6891 6.2.3 */
e87dd3
     }
e87dd3
 
e87dd3
+  // Make sure the udp size is not smaller than the incoming message so that we
e87dd3
+  // do not underflow
e87dd3
+  if (udp_size < n) udp_size = n;
e87dd3
+
e87dd3
 #ifdef HAVE_AUTH
e87dd3
   if (auth_dns)
e87dd3
     {
e87dd3
diff --git a/src/rfc1035.c b/src/rfc1035.c
e87dd3
index 917bac2..ae65702 100644
e87dd3
--- a/src/rfc1035.c
e87dd3
+++ b/src/rfc1035.c
e87dd3
@@ -1182,8 +1182,8 @@ int add_resource_record(struct dns_header *header, char *limit, int *truncp, int
e87dd3
   va_end(ap);	/* clean up variable argument pointer */
e87dd3
   
e87dd3
   j = p - sav - 2;
e87dd3
- /* this has already been checked against limit before */
e87dd3
- PUTSHORT(j, sav);     /* Now, store real RDLength */
e87dd3
+  /* this has already been checked against limit before */
e87dd3
+  PUTSHORT(j, sav);     /* Now, store real RDLength */
e87dd3
   
e87dd3
   /* check for overflow of buffer */
e87dd3
   if (limit && ((unsigned char *)limit - p) < 0)
e87dd3
@@ -1243,6 +1243,8 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
e87dd3
   int nxdomain = 0, auth = 1, trunc = 0, sec_data = 1;
e87dd3
   struct mx_srv_record *rec;
e87dd3
   size_t len;
e87dd3
+  // Make sure we do not underflow here too.
e87dd3
+  if (qlen > (limit - ((char *)header))) return 0;
e87dd3
   
e87dd3
   if (ntohs(header->ancount) != 0 ||
e87dd3
       ntohs(header->nscount) != 0 ||
e87dd3
-- 
e87dd3
2.9.5
e87dd3