From 24036ea507862c7b7898b68289c8130f85599c10 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Mon, 25 Sep 2017 18:47:15 +0100
Subject: [PATCH 3/9] Security fix, CVE-2017-14492, DHCPv6 RA heap overflow.

Fix heap overflow in IPv6 router advertisement code.
This is a potentially serious security hole, as a
crafted RA request can overflow a buffer and crash or
control dnsmasq. Attacker must be on the local network.
---
 src/radv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/radv.c b/src/radv.c
index 1032189..9b7e52c 100644
--- a/src/radv.c
+++ b/src/radv.c
@@ -198,6 +198,9 @@ void icmp6_packet(time_t now)
       /* look for link-layer address option for logging */
       if (sz >= 16 && packet[8] == ICMP6_OPT_SOURCE_MAC && (packet[9] * 8) + 8 <= sz)
 	{
+	  if ((packet[9] * 8 - 2) * 3 - 1 >= MAXDNAME) {
+	    return;
+	  }
 	  print_mac(daemon->namebuff, &packet[10], (packet[9] * 8) - 2);
 	  mac = daemon->namebuff;
 	}
-- 
2.9.5