--- linux-3.10/drivers/net/Kconfig
+++ linux-3.10/drivers/net/Kconfig
@@ -251,6 +251,17 @@
     depends on AVM_CPMAC && LANTIQ
     default n
 
+config YF_PATCHKERNEL_NET
+	tristate "LKM to remove/patch wrong BUG_ON statements in network code"
+	depends on TUN && m
+	default m
+	---help---
+	  This affected code has to be built as module, do not select 'Y' here.
+	  The built module changes three functions in the networking core, 
+	  where AVM has inserted BUG_ON statements, which lead to an unusable
+	  TUN/TAP interface and to problems with IPv4 forwarding. To circumvent
+	  these problems with an original kernel from AVM, this module may be
+	  loaded prior to receive of any packets via a TUN interface.
 
 endif # NET_CORE
 
--- linux-3.10/drivers/net/Makefile
+++ linux-3.10/drivers/net/Makefile
@@ -19,6 +19,7 @@
 obj-$(CONFIG_RIONET) += rionet.o
 obj-$(CONFIG_NET_TEAM) += team/
 obj-$(CONFIG_TUN) += tun.o
+obj-$(CONFIG_YF_PATCHKERNEL_NET) += yf_patchkernel.o
 obj-$(CONFIG_VETH) += veth.o
 obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
 obj-$(CONFIG_VXLAN) += vxlan.o