dnsmasq/dnsmasq-2.77-underflow.patch

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From 9d2757b9714523b53ed487b57e740f1b5beb4e0b 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 | 6 ++++--
3 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/src/edns0.c b/src/edns0.c
index 9c6dbcb..268fbe7 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 d1962be..6b9c16e 100644
--- a/src/forward.c
+++ b/src/forward.c
@@ -1417,6 +1417,10 @@ 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 0bf3bcc..3513455 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -1198,8 +1198,8 @@ int add_resource_record(struct dns_header *header, char *limit, int *truncp, int
va_end(ap); /* clean up variable argument pointer */
j = p - sav - 2;
- /* this has already been checked against limit before */
- PUTSHORT(j, sav); /* Now, store real RDLength */
+ /* this has already been checked against limit before */
+ PUTSHORT(j, sav); /* Now, store real RDLength */
/* check for overflow of buffer */
if (limit && ((unsigned char *)limit - p) < 0)
@@ -1259,6 +1259,8 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
int nxdomain = 0, auth = 1, trunc = 0, sec_data = 1;
struct mx_srv_record *rec;
size_t len;
+ // Make sure we do not underflow here too.
+ if (qlen > (limit - ((char *)header))) return 0;
if (ntohs(header->ancount) != 0 ||
ntohs(header->nscount) != 0 ||
--
2.9.5