From: Fernando Fernandez Mancera Date: Wed, 21 Jan 2026 19:44:08 +0000 (+0100) Subject: ipv6: use the right ifindex when replying to icmpv6 from localhost X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=03cbcdf93866e61beb0063392e6dbb701f03aea2;p=thirdparty%2Fkernel%2Flinux.git ipv6: use the right ifindex when replying to icmpv6 from localhost When replying to a ICMPv6 echo request that comes from localhost address the right output ifindex is 1 (lo) and not rt6i_idev dev index. Use the skb device ifindex instead. This fixes pinging to a local address from localhost source address. $ ping6 -I ::1 2001:1:1::2 -c 3 PING 2001:1:1::2 (2001:1:1::2) from ::1 : 56 data bytes 64 bytes from 2001:1:1::2: icmp_seq=1 ttl=64 time=0.037 ms 64 bytes from 2001:1:1::2: icmp_seq=2 ttl=64 time=0.069 ms 64 bytes from 2001:1:1::2: icmp_seq=3 ttl=64 time=0.122 ms 2001:1:1::2 ping statistics 3 packets transmitted, 3 received, 0% packet loss, time 2032ms rtt min/avg/max/mdev = 0.037/0.076/0.122/0.035 ms Fixes: 1b70d792cf67 ("ipv6: Use rt6i_idev index for echo replies to a local address") Signed-off-by: Fernando Fernandez Mancera Reviewed-by: David Ahern Link: https://patch.msgid.link/20260121194409.6749-1-fmancera@suse.de Signed-off-by: Jakub Kicinski --- diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index 5d2f90babaa5..9d37e7711bc2 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -965,7 +965,9 @@ static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb) fl6.daddr = ipv6_hdr(skb)->saddr; if (saddr) fl6.saddr = *saddr; - fl6.flowi6_oif = icmp6_iif(skb); + fl6.flowi6_oif = ipv6_addr_loopback(&fl6.daddr) ? + skb->dev->ifindex : + icmp6_iif(skb); fl6.fl6_icmp_type = type; fl6.flowi6_mark = mark; fl6.flowi6_uid = sock_net_uid(net, NULL);