From 9a753c49ea7053f3592f9ec1ce9d97882edb332d Mon Sep 17 00:00:00 2001 From: Kevin Darbyshire-Bryant Date: Thu, 7 Sep 2017 03:58:23 +0100 Subject: [PATCH] dnsmasq: backport official fix for CVE-2017-13704 Remove LEDE partial fix for CVE-2017-13704. Backport official fix from upstream. Signed-off-by: Kevin Darbyshire-Bryant Signed-off-by: Hans Dedecker (PKG_RELEASE increase) --- package/network/services/dnsmasq/Makefile | 2 +- .../025-backport-fix-CVE-2017-13704.patch | 94 +++++++++++++++++++ .../patches/025-fix-CVE-2017-13704.patch | 37 -------- 3 files changed, 95 insertions(+), 38 deletions(-) create mode 100644 package/network/services/dnsmasq/patches/025-backport-fix-CVE-2017-13704.patch delete mode 100644 package/network/services/dnsmasq/patches/025-fix-CVE-2017-13704.patch diff --git a/package/network/services/dnsmasq/Makefile b/package/network/services/dnsmasq/Makefile index bd7f61010d..d200d1d9e9 100644 --- a/package/network/services/dnsmasq/Makefile +++ b/package/network/services/dnsmasq/Makefile @@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk PKG_NAME:=dnsmasq PKG_VERSION:=2.77 -PKG_RELEASE:=10 +PKG_RELEASE:=11 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz PKG_SOURCE_URL:=http://thekelleys.org.uk/dnsmasq/ diff --git a/package/network/services/dnsmasq/patches/025-backport-fix-CVE-2017-13704.patch b/package/network/services/dnsmasq/patches/025-backport-fix-CVE-2017-13704.patch new file mode 100644 index 0000000000..bba9a08060 --- /dev/null +++ b/package/network/services/dnsmasq/patches/025-backport-fix-CVE-2017-13704.patch @@ -0,0 +1,94 @@ +From 63437ffbb58837b214b4b92cb1c54bc5f3279928 Mon Sep 17 00:00:00 2001 +From: Simon Kelley +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 + diff --git a/package/network/services/dnsmasq/patches/025-fix-CVE-2017-13704.patch b/package/network/services/dnsmasq/patches/025-fix-CVE-2017-13704.patch deleted file mode 100644 index 8848131dac..0000000000 --- a/package/network/services/dnsmasq/patches/025-fix-CVE-2017-13704.patch +++ /dev/null @@ -1,37 +0,0 @@ -From 38af9b1ac3242a4128e88069c495024caa565f0e Mon Sep 17 00:00:00 2001 -From: Kevin Darbyshire-Bryant -Date: Tue, 29 Aug 2017 12:35:40 +0100 -Subject: [PATCH] forward.c: fix CVE-2017-13704 - -Fix SIGSEGV in rfc1035.c answer_request() line 1228 where memset() -is called with header & limit pointing at the same address and thus -tries to clear memory from before the buffer begins. - -answer_request() is called with an invalid edns packet size provided by -the client. Ensure the udp_size provided by the client is bounded by -512 and configured maximum as per RFC 6891 6.2.3 "Values lower than 512 -MUST be treated as equal to 512" - -The client that exposed the problem provided a payload udp size of 0. - -Signed-off-by: Kevin Darbyshire-Bryant ---- - src/forward.c | 2 ++ - 1 file changed, 2 insertions(+) - -diff --git a/src/forward.c b/src/forward.c -index f22556a..62c5a5a 100644 ---- a/src/forward.c -+++ b/src/forward.c -@@ -1408,6 +1408,8 @@ void receive_query(struct listener *listen, time_t now) - defaults to 512 */ - if (udp_size > daemon->edns_pktsz) - udp_size = daemon->edns_pktsz; -+ if (udp_size < 512) -+ udp_size = 512; /* RFC 6891 6.2.3 */ - } - - #ifdef HAVE_AUTH --- -2.7.4 - -- 2.30.2