On any driver that advertises NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM but not the superseding NETIF_F_HW_CSUM (e.g., ice/bnxt_en), the kernel incorrectly attempts GSO on IPv6 packets with extension headers. Because the NETIF_F_IPV6_CSUM feature is incompatible with these headers, the failure results in a `skb_warn_bad_offload` warning and a collapse of throughput, as observed with GREoIPv6 traffic. Mask NETIF_F_IPV6_CSUM, NETIF_F_TSO6 and NETIF_F_GSO_UDP_L4 in gso_features_check if the IPv6 header contains extension headers. The exception is a BIG TCP extension, which, as stated in commit 68e068cabd2c6c53 (net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets): "The feature is only enabled on devices that support BIG TCP TSO. The header is only present for PF_PACKET taps like tcpdump, and not transmitted by physical devices." kernel log output (truncated): WARNING: CPU: 1 PID: 5273 at net/core/dev.c:3535 skb_warn_bad_offload+0x81/0x140 ... Call Trace: skb_checksum_help+0x12a/0x1f0 ? netif_skb_features+0xc1/0x2e0 validate_xmit_skb+0x1a3/0x2d0 validate_xmit_skb_list+0x4f/0x80 sch_direct_xmit+0x1a2/0x380 __dev_xmit_skb+0x242/0x670 __dev_queue_xmit+0x3fc/0x7f0 ? srso_alias_return_thunk+0x5/0xfbef5 ? ip6_rt_copy_init+0xf0/0x290 ? srso_alias_return_thunk+0x5/0xfbef5 ? selinux_ip_postroute+0x1c5/0x420 ? srso_alias_return_thunk+0x5/0xfbef5 ip6_finish_output2+0x25e/0x5d0 ? srso_alias_return_thunk+0x5/0xfbef5 ? nf_hook_slow+0x47/0xf0 ? srso_alias_return_thunk+0x5/0xfbef5 ip6_finish_output+0x1fc/0x3f0 ip6_tnl_xmit+0x608/0xc00 [ip6_tunnel] ? srso_alias_return_thunk+0x5/0xfbef5 ip6gre_tunnel_xmit+0x1c0/0x390 [ip6_gre] dev_hard_start_xmit+0x63/0x1c0 __dev_queue_xmit+0x6d0/0x7f0 ? srso_alias_return_thunk+0x5/0xfbef5 ? chacha_block_generic+0x72/0xd0 ? srso_alias_return_thunk+0x5/0xfbef5 ? selinux_ip_postroute+0x1c5/0x420 ip6_finish_output2+0x214/0x5d0 ? srso_alias_return_thunk+0x5/0xfbef5 ? nf_hook_slow+0x47/0xf0 ip6_finish_output+0x1fc/0x3f0 ip6_xmit+0x2ca/0x6f0 ? __pfx_dst_output+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? nf_hook_slow+0x47/0xf0 ip6_finish_output+0x1fc/0x3f0 ip6_xmit+0x2ca/0x6f0 ? __pfx_dst_output+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __sk_dst_check+0x41/0xc0 ? srso_alias_return_thunk+0x5/0xfbef5 ? inet6_csk_route_socket+0x12e/0x200 inet6_csk_xmit+0xeb/0x150 __tcp_transmit_skb+0x555/0xa80 tcp_write_xmit+0x32a/0xe90 ? srso_alias_return_thunk+0x5/0xfbef5 ? skb_do_copy_data_nocache+0xc9/0x150 tcp_sendmsg_locked+0x437/0x1110 ? srso_alias_return_thunk+0x5/0xfbef5 tcp_sendmsg+0x2f/0x50 ... skb linear: 00000000: e4 3d 1a 7d ec 30 e4 3d 1a 7e 5d 90 86 dd 60 0e skb linear: 00000010: 00 0a 1b 34 3c 40 20 11 00 00 00 00 00 00 00 00 skb linear: 00000020: 00 00 00 00 00 12 20 11 00 00 00 00 00 00 00 00 skb linear: 00000030: 00 00 00 00 00 11 2f 00 04 01 04 01 01 00 00 00 skb linear: 00000040: 86 dd 60 0e 00 0a 1b 00 06 40 20 23 00 00 00 00 skb linear: 00000050: 00 00 00 00 00 00 00 00 00 12 20 23 00 00 00 00 skb linear: 00000060: 00 00 00 00 00 00 00 00 00 11 bf 96 14 51 13 f9 skb linear: 00000070: ae 27 a0 a8 2b e3 80 18 00 40 5b 6f 00 00 01 01 skb linear: 00000080: 08 0a 42 d4 50 d5 4b 70 f8 1a Fixes: 04c20a9356f283da ("net: skip offload for NETIF_F_IPV6_CSUM if ipv6 header contains extension") Reported-by: Tianhao Zhao Suggested-by: Michal Schmidt Suggested-by: Willem de Bruijn Signed-off-by: Jakub Ramaseuski --- --- net/core/dev.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/core/dev.c b/net/core/dev.c index b28ce68830b2b..1d8a4d1da911e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3778,6 +3778,18 @@ static netdev_features_t gso_features_check(const struct sk_buff *skb, if (!(iph->frag_off & htons(IP_DF))) features &= ~NETIF_F_TSO_MANGLEID; } + + /* NETIF_F_IPV6_CSUM does not support IPv6 extension headers, + * so neither does TSO that depends on it. + */ + if (features & NETIF_F_IPV6_CSUM && + (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6 || + (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 && + vlan_get_protocol(skb) == htons(ETH_P_IPV6))) && + skb_transport_header_was_set(skb) && + skb_network_header_len(skb) != sizeof(struct ipv6hdr) && + !ipv6_has_hopopt_jumbo(skb)) + features &= ~(NETIF_F_IPV6_CSUM | NETIF_F_TSO6 | NETIF_F_GSO_UDP_L4); return features; } -- 2.50.1