[Buildroot] [PATCH] package/dnsmasq: fix CVE-2023-28450

[Daniel Lang]

Adds the upstream patch that fixes the CVE.
No new release so far.

Signed-off-by: Daniel Lang <dalang at gmx.at>
---
 ...default-maximum-dns-udp-package-size.patch | 64 +++++++++++++++++++
 package/dnsmasq/dnsmasq.mk                    |  3 +
 2 files changed, 67 insertions(+)
 create mode 100644 package/dnsmasq/0001-set-default-maximum-dns-udp-package-size.patch

diff --git a/package/dnsmasq/0001-set-default-maximum-dns-udp-package-size.patch b/package/dnsmasq/0001-set-default-maximum-dns-udp-package-size.patch
new file mode 100644
index 0000000000..4dd17ec069
--- /dev/null
+++ b/package/dnsmasq/0001-set-default-maximum-dns-udp-package-size.patch
@@ -0,0 +1,64 @@
+From eb92fb32b746f2104b0f370b5b295bb8dd4bd5e5 Mon Sep 17 00:00:00 2001
+From: Simon Kelley <simon at thekelleys.org.uk>
+Date: Tue, 7 Mar 2023 22:07:46 +0000
+Subject: [PATCH] Set the default maximum DNS UDP packet size to 1232.
+Upstream: https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=eb92fb32b746f2104b0f370b5b295bb8dd4bd5e5
+
+http://www.dnsflagday.net/2020/ refers.
+
+Thanks to Xiang Li for the prompt.
+
+[dalang at gmx.at: backport from upstream]
+Signed-off-by: Daniel Lang <dalang at gmx.at>
+---
+ CHANGELOG     | 9 ++++++++
+ man/dnsmasq.8 | 3 ++-
+ src/config.h  | 2 +-
+ 3 files changed, 12 insertions(+), 2 deletions(-)
+
+diff --git a/CHANGELOG b/CHANGELOG
+index 3af20cf..52d8678 100644
+--- a/CHANGELOG
++++ b/CHANGELOG
+@@ -1,3 +1,12 @@ version 2.90
++version 2.90
++	Set the default maximum DNS UDP packet sice to 1232. This
++	has been the recommended value since 2020 because it's the
++	largest value that avoid fragmentation, and fragmentation
++	is just not reliable on the modern internet, especially
++	for IPv6. It's still possible to override this with
++	--edns-packet-max for special circumstances.
++
++
+ version 2.89
+         Fix bug introduced in 2.88 (commit fe91134b) which can result
+ 	in corruption of the DNS cache internal data structures and
+diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
+index 41e2e04..5acb935 100644
+--- a/man/dnsmasq.8
++++ b/man/dnsmasq.8
+@@ -183,7 +183,8 @@ to zero completely disables DNS function, leaving only DHCP and/or TFTP.
+ .TP
+ .B \-P, --edns-packet-max=<size>
+ Specify the largest EDNS.0 UDP packet which is supported by the DNS
+-forwarder. Defaults to 4096, which is the RFC5625-recommended size.
++forwarder. Defaults to 1232, which is the recommended size following the
++DNS flag day in 2020. Only increase if you know what you are doing.
+ .TP
+ .B \-Q, --query-port=<query_port>
+ Send outbound DNS queries from, and listen for their replies on, the
+diff --git a/src/config.h b/src/config.h
+index 1e7b30f..37b374e 100644
+--- a/src/config.h
++++ b/src/config.h
+@@ -19,7 +19,7 @@
+ #define CHILD_LIFETIME 150 /* secs 'till terminated (RFC1035 suggests > 120s) */
+ #define TCP_MAX_QUERIES 100 /* Maximum number of queries per incoming TCP connection */
+ #define TCP_BACKLOG 32  /* kernel backlog limit for TCP connections */
+-#define EDNS_PKTSZ 4096 /* default max EDNS.0 UDP packet from RFC5625 */
++#define EDNS_PKTSZ 1232 /* default max EDNS.0 UDP packet from from  /dnsflagday.net/2020 */
+ #define SAFE_PKTSZ 1232 /* "go anywhere" UDP packet size, see https://dnsflagday.net/2020/ */
+ #define KEYBLOCK_LEN 40 /* choose to minimise fragmentation when storing DNSSEC keys */
+ #define DNSSEC_WORK 50 /* Max number of queries to validate one question */
+--
+2.20.1
diff --git a/package/dnsmasq/dnsmasq.mk b/package/dnsmasq/dnsmasq.mk
index 58c5390433..9c05857f22 100644
--- a/package/dnsmasq/dnsmasq.mk
+++ b/package/dnsmasq/dnsmasq.mk
@@ -17,6 +17,9 @@ DNSMASQ_LICENSE_FILES = COPYING COPYING-v3
 DNSMASQ_CPE_ID_VENDOR = thekelleys
 DNSMASQ_SELINUX_MODULES = dnsmasq
 
+# 0001-set-default-maximum-dns-udp-package-size.patch
+DNSMASQ_IGNORE_CVES += CVE-2023-28450
+
 DNSMASQ_I18N = $(if $(BR2_SYSTEM_ENABLE_NLS),-i18n)
 
 ifneq ($(BR2_PACKAGE_DNSMASQ_DHCP),y)
-- 
2.40.1