dnsmasq/dnsmasq-2.77-underflow.patch

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From 684bede049a006a0a47ce88f017ada9f73bf4430 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/forward.c | 4 ++++
src/rfc1035.c | 3 +++
3 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/src/edns0.c b/src/edns0.c
index d75d3cc..7d8cf7f 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/forward.c b/src/forward.c
index ed9c8f6..77059ed 100644
--- a/src/forward.c
+++ b/src/forward.c
@@ -1542,6 +1542,10 @@ void receive_query(struct listener *listen, time_t now)
udp_size = PACKETSZ; /* Sanity check - can't reduce below default. RFC 6891 6.2.3 */
}
+ // Make sure the udp size is not smaller than the incoming message so that we
+ // do not underflow
+ if (udp_size < n) udp_size = n;
+
#ifdef HAVE_AUTH
if (auth_dns)
{
diff --git a/src/rfc1035.c b/src/rfc1035.c
index f1edc45..15041cc 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -1326,6 +1326,9 @@ 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;
+
/* never answer queries with RD unset, to avoid cache snooping. */
if (ntohs(header->ancount) != 0 ||
ntohs(header->nscount) != 0 ||
--
2.21.1