From f23f4be3cb72d307806e3d3ca14779f69ac5494c Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Mon, 25 Sep 2017 18:52:50 +0100
Subject: [PATCH 3/7] Security fix, CVE-2017-14493, DHCPv6 - Stack buffer
 overflow.

commit 3d4ff1ba8419546490b464418223132529514033 upstream
git://thekelleys.org.uk/dnsmasq

Fix stack overflow in DHCPv6 code. An attacker who can send
a DHCPv6 request to dnsmasq can overflow the stack frame and
crash or control dnsmasq.

Upstream-Status: Backport

Signed-off-by: Zhang Xiao <xiao.zhang@windriver.com>
---
 src/rfc3315.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/rfc3315.c b/src/rfc3315.c
index 73bdee4..8d18a28 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -206,6 +206,9 @@ static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz,
   /* RFC-6939 */
   if ((opt = opt6_find(opts, end, OPTION6_CLIENT_MAC, 3)))
     {
+      if (opt6_len(opt) - 2 > DHCP_CHADDR_MAX) {
+        return 0;
+      }
       state->mac_type = opt6_uint(opt, 0, 2);
       state->mac_len = opt6_len(opt) - 2;
       memcpy(&state->mac[0], opt6_ptr(opt, 2), state->mac_len);
-- 
2.11.0