95 lines
2.9 KiB
Diff
95 lines
2.9 KiB
Diff
|
From 63437ffbb58837b214b4b92cb1c54bc5f3279928 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Simon Kelley <simon@thekelleys.org.uk>
|
||
|
|
Date: Wed, 6 Sep 2017 22:34:21 +0100
|
||
|
|
Subject: [PATCH] Fix CVE-2017-13704, which resulted in a crash on a large DNS
|
||
|
|
query.
|
||
|
|
|
||
|
|
A DNS query recieved by UDP which exceeds 512 bytes (or the EDNS0 packet size,
|
||
|
|
if different.) is enough to cause SIGSEGV.
|
||
|
|
---
|
||
|
|
CHANGELOG | 7 +++++++
|
||
|
|
src/auth.c | 5 -----
|
||
|
|
src/forward.c | 8 ++++++++
|
||
|
|
src/rfc1035.c | 5 -----
|
||
|
|
4 files changed, 15 insertions(+), 10 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/CHANGELOG b/CHANGELOG
|
||
|
|
index 3a640f3..7e65912 100644
|
||
|
|
--- a/CHANGELOG
|
||
|
|
+++ b/CHANGELOG
|
||
|
|
@@ -17,6 +17,13 @@ version 2.78
|
||
|
|
--strict-order active. Thanks to Hans Dedecker
|
||
|
|
for the patch
|
||
|
|
|
||
|
|
+ Fix regression in 2.77, ironically added as a security
|
||
|
|
+ improvement, which resulted in a crash when a DNS
|
||
|
|
+ query exceeded 512 bytes (or the EDNS0 packet size,
|
||
|
|
+ if different.) Thanks to Christian Kujau, Arne Woerner
|
||
|
|
+ Juan Manuel Fernandez and Kevin Darbyshire-Bryant for
|
||
|
|
+ chasing this one down. CVE-2017-13704 applies.
|
||
|
|
+
|
||
|
|
|
||
|
|
version 2.77
|
||
|
|
Generate an error when configured with a CNAME loop,
|
||
|
|
diff --git a/src/auth.c b/src/auth.c
|
||
|
|
index 2c24e16..7f95f98 100644
|
||
|
|
--- a/src/auth.c
|
||
|
|
+++ b/src/auth.c
|
||
|
|
@@ -119,11 +119,6 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
|
||
|
|
struct cname *a, *candidate;
|
||
|
|
unsigned int wclen;
|
||
|
|
|
||
|
|
- /* Clear buffer beyond request to avoid risk of
|
||
|
|
- information disclosure. */
|
||
|
|
- memset(((char *)header) + qlen, 0,
|
||
|
|
- (limit - ((char *)header)) - qlen);
|
||
|
|
-
|
||
|
|
if (ntohs(header->qdcount) == 0 || OPCODE(header) != QUERY )
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
diff --git a/src/forward.c b/src/forward.c
|
||
|
|
index f22556a..e3fa94b 100644
|
||
|
|
--- a/src/forward.c
|
||
|
|
+++ b/src/forward.c
|
||
|
|
@@ -1188,6 +1188,10 @@ void receive_query(struct listener *listen, time_t now)
|
||
|
|
(msg.msg_flags & MSG_TRUNC) ||
|
||
|
|
(header->hb3 & HB3_QR))
|
||
|
|
return;
|
||
|
|
+
|
||
|
|
+ /* Clear buffer beyond request to avoid risk of
|
||
|
|
+ information disclosure. */
|
||
|
|
+ memset(daemon->packet + n, 0, daemon->edns_pktsz - n);
|
||
|
|
|
||
|
|
source_addr.sa.sa_family = listen->family;
|
||
|
|
|
||
|
|
@@ -1688,6 +1692,10 @@ unsigned char *tcp_request(int confd, time_t now,
|
||
|
|
|
||
|
|
if (size < (int)sizeof(struct dns_header))
|
||
|
|
continue;
|
||
|
|
+
|
||
|
|
+ /* Clear buffer beyond request to avoid risk of
|
||
|
|
+ information disclosure. */
|
||
|
|
+ memset(payload + size, 0, 65536 - size);
|
||
|
|
|
||
|
|
query_count++;
|
||
|
|
|
||
|
|
diff --git a/src/rfc1035.c b/src/rfc1035.c
|
||
|
|
index 26f5301..af2fe46 100644
|
||
|
|
--- a/src/rfc1035.c
|
||
|
|
+++ b/src/rfc1035.c
|
||
|
|
@@ -1223,11 +1223,6 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
|
||
|
|
struct mx_srv_record *rec;
|
||
|
|
size_t len;
|
||
|
|
|
||
|
|
- /* Clear buffer beyond request to avoid risk of
|
||
|
|
- information disclosure. */
|
||
|
|
- memset(((char *)header) + qlen, 0,
|
||
|
|
- (limit - ((char *)header)) - qlen);
|
||
|
|
-
|
||
|
|
if (ntohs(header->ancount) != 0 ||
|
||
|
|
ntohs(header->nscount) != 0 ||
|
||
|
|
ntohs(header->qdcount) == 0 ||
|
||
|
|
--
|
||
|
|
1.7.10.4
|
||
|
|
|