From ef01724fa235a228e3d3e8b117e89403cd8feb25 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ricardo=20B=2E=20Marli=C3=A8re?= Date: Mon, 6 Jul 2026 13:24:04 -0300 Subject: [PATCH] selftests/net: Fix tun IPv6 test addresses to avoid 6to4 range MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The IPv6 addresses used for the tun_vnet_udptnl fixture currently fall in the 2002::/16 prefix, which is reserved for the 6to4 transition mechanism (RFC 3056). On systems where the sit module is loaded, the kernel automatically claims 2002::/16 as a 6to4 tunnel prefix. When the test assigns a 2002:: address to a TUN interface, sit registers a competing local route for the same address. This ambiguity breaks the GENEVE decapsulation path: packets injected via the TUN fd are not delivered to the test socket, causing the IPv6-outer gtgso send_gso_packet variants to fail. Replace all four IPv6 test addresses with addresses from the fd00:db8::/32 range, which is part of the ULA space (fc00::/7, RFC 4193) and carries no special kernel semantics. Fixes: 24e59f26eef2 ("selftest: tun: Add helpers for GSO over UDP tunnel") Signed-off-by: Ricardo B. Marlière Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260706-b4-net_tun_addr-v1-1-3d3cb2473560@suse.com Signed-off-by: Jakub Kicinski --- tools/testing/selftests/net/tun.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c index cf106a49b55e..abe488bac50b 100644 --- a/tools/testing/selftests/net/tun.c +++ b/tools/testing/selftests/net/tun.c @@ -42,19 +42,19 @@ static struct in_addr param_ipaddr4_inner_src = { }; static struct in6_addr param_ipaddr6_outer_dst = { - { { 0x20, 0x02, 0x0d, 0xb8, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 } }, + { { 0xfd, 0x00, 0x0d, 0xb8, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 } }, }; static struct in6_addr param_ipaddr6_outer_src = { - { { 0x20, 0x02, 0x0d, 0xb8, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2 } }, + { { 0xfd, 0x00, 0x0d, 0xb8, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2 } }, }; static struct in6_addr param_ipaddr6_inner_dst = { - { { 0x20, 0x02, 0x0d, 0xb8, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 } }, + { { 0xfd, 0x00, 0x0d, 0xb8, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 } }, }; static struct in6_addr param_ipaddr6_inner_src = { - { { 0x20, 0x02, 0x0d, 0xb8, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2 } }, + { { 0xfd, 0x00, 0x0d, 0xb8, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2 } }, }; #ifndef BIT