With NETFILTER_XT_TARGET_TEE=y and IP6_NF_IPTABLES=m, we get a link error when referencing the NF_DUP_IPV6 module: net/netfilter/xt_TEE.o: In function `tee_tg6': xt_TEE.c:(.text+0x14): undefined reference to `nf_dup_ipv6' The problem here is the 'select NF_DUP_IPV6 if IP6_NF_IPTABLES' that forces NF_DUP_IPV6 to be =m as well rather than setting it to =y as was intended here. Adding a soft dependency on IP6_NF_IPTABLES avoids that broken configuration. Fixes: 5d400a4933e8 ("netfilter: Kconfig: Change select IPv6 dependencies") Cc: Máté Eckl <ecklm94@xxxxxxxxx> Cc: Taehee Yoo <ap420073@xxxxxxxxx> Link: https://patchwork.ozlabs.org/patch/999498/ Link: https://lore.kernel.org/patchwork/patch/960062/ Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- Resending this one, I had sent another version before last July, and then Máté Eckl did a combined version that I thought was sufficient, but I had left my old patch in the randconfig build tree, so I failed to notice that it was still required. Taehee Yoo also prepared a patch to address this, but that patch was never merged, and I suspect it did not catch all cases either, so we still need mine. --- net/netfilter/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 964bc317ad0a..ca3ba7548998 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -1008,6 +1008,7 @@ config NETFILTER_XT_TARGET_TEE depends on NETFILTER_ADVANCED depends on IPV6 || IPV6=n depends on !NF_CONNTRACK || NF_CONNTRACK + depends on IP6_NF_IPTABLES || !IP6_NF_IPTABLES select NF_DUP_IPV4 select NF_DUP_IPV6 if IP6_NF_IPTABLES ---help--- -- 2.20.0