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From e4ae220ee00dcad20a716432badd3210b442ddb4 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 6/7] Security fix, CVE-2017-14495, OOM in DNS response
creation.
commit 51eadb692a5123b9838e5a68ecace3ac579a3a45 upstream
git://thekelleys.org.uk/dnsmasq
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.
Upstream-Status: Backport
Signed-off-by: Zhang Xiao <xiao.zhang@windriver.com>
---
src/edns0.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/src/edns0.c b/src/edns0.c
index a2ef0ea..f48c084 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 */
--
2.11.0
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