-diff -NurpP --minimal linux-2.6.21.b/net/ipv4/netfilter/Kconfig linux-2.6.21.a/net/ipv4/netfilter/Kconfig
---- linux-2.6.21.b/net/ipv4/netfilter/Kconfig 2007-05-30 11:11:52.000000000 +0200
-+++ linux-2.6.21.a/net/ipv4/netfilter/Kconfig 2007-05-30 11:18:08.000000000 +0200
-@@ -668,5 +668,15 @@ config IP_NF_ARP_MANGLE
- Allows altering the ARP packet payload: source and destination
- hardware and network addresses.
+diff -ur linux-5.9/net/ipv4/netfilter.org/Kconfig linux-5.9/net/ipv4/netfilter/Kconfig
+--- linux-5.9/net/ipv4/netfilter.org/Kconfig 2020-10-11 23:15:50.000000000 +0200
++++ linux-5.9/net/ipv4/netfilter/Kconfig 2020-11-03 13:07:22.874511004 +0100
+@@ -356,5 +356,15 @@
+
+ endif # IP_NF_ARPTABLES
+config IP_NF_TARGET_IPV4OPTSSTRIP
+ tristate 'IPV4OPTSSTRIP target support'
+
endmenu
---- linux-5.2/net/ipv4/netfilter/Makefile~ 2019-07-08 00:41:56.000000000 +0200
-+++ linux-5.2/net/ipv4/netfilter/Makefile 2019-07-08 09:01:35.241471623 +0200
-@@ -48,6 +48,7 @@ obj-$(CONFIG_IP_NF_MATCH_RPFILTER) += ip
+diff -ur linux-5.9/net/ipv4/netfilter.org/Makefile linux-5.9/net/ipv4/netfilter/Makefile
+--- linux-5.9/net/ipv4/netfilter.org/Makefile 2020-10-11 23:15:50.000000000 +0200
++++ linux-5.9/net/ipv4/netfilter/Makefile 2020-11-03 13:07:22.874511004 +0100
+@@ -48,6 +48,7 @@
# targets
obj-$(CONFIG_IP_NF_TARGET_CLUSTERIP) += ipt_CLUSTERIP.o
obj-$(CONFIG_IP_NF_TARGET_ECN) += ipt_ECN.o
+ unsigned char *optiph;
+ int l;
+
-+ if (!skb_make_writable(skb, skb->len))
++ if (skb_ensure_writable(skb, skb->len))
+ return NF_DROP;
+
+ iph = ip_hdr(skb);