dnsmasq/backport-dnsmasq-2.77-underflow.patch

From 0e581ae7b2d3b181f22f71d5a0b7ace0bf90089f Mon Sep 17 00:00:00 2001
From: Doran Moppert <dmoppert@redhat.com>
Date: Tue, 26 Sep 2017 14:48:20 +0930
Subject: [PATCH] google patch hand-applied

---
 src/edns0.c   | 10 +++++-----
 src/rfc1035.c |  3 +++
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/edns0.c b/src/edns0.c
index c498eb1..0eb3873 100644
--- a/src/edns0.c
+++ b/src/edns0.c
@@ -212,11 +212,11 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
       /* Copy back any options */
       if (buff)
 	{
-          if (p + rdlen > limit)
-          {
-            free(buff);
-            return plen; /* Too big */
-          }
+	  if (p + rdlen > limit)
+	  {
+	    free(buff);
+	    return plen; /* Too big */
+	  }
 	  memcpy(p, buff, rdlen);
 	  free(buff);
 	  p += rdlen;
diff --git a/src/rfc1035.c b/src/rfc1035.c
index 5c0df56..7e01459 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -1425,6 +1425,9 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
   size_t len;
   int rd_bit = (header->hb3 & HB3_RD);
 
+  // Make sure we do not underflow here too.
+  if (qlen > (limit - ((char *)header))) return 0;
+
   if (stale)
     *stale = 0;
   
-- 
2.38.1