dnsmasq/backport-dnsmasq-2.77-underflow.patch

From 6fda9cd7cba519a8aa96b43ebc34cb6c46b3bfe7 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

Reference:
https://src.fedoraproject.org/rpms/dnsmasq/blob/f40/dnsmasq-2.77-underflow.patch
---
 src/edns0.c   | 10 +++++-----
 src/rfc1035.c |  5 ++++-
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/edns0.c b/src/edns0.c
index 598478f..72127e5 100644
--- a/src/edns0.c
+++ b/src/edns0.c
@@ -209,11 +209,11 @@ 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 387d894..7fb1468 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -1581,7 +1581,10 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
   size_t len;
   int rd_bit = (header->hb3 & HB3_RD);
   int count = 255; /* catch loops */
-  
+
+  // Make sure we do not underflow here too.
+  if (qlen > (limit - ((char *)header))) return 0;
+
   if (stale)
     *stale = 0;
 
-- 
2.43.0