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From 51eadb692a5123b9838e5a68ecace3ac579a3a45 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Mon, 25 Sep 2017 20:16:50 +0100
Subject: [PATCH] Security fix, CVE-2017-14495, OOM in DNS response creation.
Fix out-of-memory Dos vulnerability. An attacker which can
send malicious DNS queries to dnsmasq can trigger memory
allocations in the add_pseudoheader function
The allocated memory is never freed which leads to a DoS
through memory exhaustion. dnsmasq is vulnerable only
if one of the following option is specified:
--add-mac, --add-cpe-id or --add-subnet.
CVE: CVE-2017-14495
Upstream-Status: Backport
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
---
CHANGELOG | 12 ++++++++++++
src/edns0.c | 8 +++++++-
2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/CHANGELOG b/CHANGELOG
index 8fe00ed..9523329 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -70,6 +70,18 @@ version 2.78
Credit to Felix Wilhelm, Fermin J. Serna, Gabriel Campana
and Kevin Hamacher of the Google Security Team for
finding this.
+
+ Fix out-of-memory Dos vulnerability. An attacker which can
+ send malicious DNS queries to dnsmasq can trigger memory
+ allocations in the add_pseudoheader function
+ The allocated memory is never freed which leads to a DoS
+ through memory exhaustion. dnsmasq is vulnerable only
+ if one of the following option is specified:
+ --add-mac, --add-cpe-id or --add-subnet.
+ CVE-2017-14495 applies.
+ Credit to Felix Wilhelm, Fermin J. Serna, Gabriel Campana
+ and Kevin Hamacher of the Google Security Team for
+ finding this.
version 2.77
diff --git a/src/edns0.c b/src/edns0.c
index 95b74ee..89b2692 100644
--- a/src/edns0.c
+++ b/src/edns0.c
@@ -192,9 +192,15 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
!(p = skip_section(p,
ntohs(header->ancount) + ntohs(header->nscount) + ntohs(header->arcount),
header, plen)))
+ {
+ free(buff);
return plen;
+ }
if (p + 11 > limit)
- return plen; /* Too big */
+ {
+ free(buff);
+ return plen; /* Too big */
+ }
*p++ = 0; /* empty name */
PUTSHORT(T_OPT, p);
PUTSHORT(udp_sz, p); /* max packet length, 512 if not given in EDNS0 header */
--
1.7.10.4
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