From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Subject: [PATCH net v2] gso_segment: Reset skb->mac_len after modifying network header Date: Thu, 13 Sep 2018 16:43:07 +0200 Message-ID: <20180913144306.9077-1-toke@toke.dk> References: <153670437243.12756.693381878569982309.stgit@alrua-kau> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , cake@lists.bufferbloat.net, David Miller , Eric Dumazet , Dave Taht To: netdev@vger.kernel.org Return-path: Received: from mail.toke.dk ([52.28.52.200]:34193 "EHLO mail.toke.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726580AbeIMTyl (ORCPT ); Thu, 13 Sep 2018 15:54:41 -0400 In-Reply-To: <153670437243.12756.693381878569982309.stgit@alrua-kau> References: Sender: netdev-owner@vger.kernel.org List-ID: When splitting a GSO segment that consists of encapsulated packets, the skb->mac_len of the segments can end up being set wrong, causing packet drops in particular when using act_mirred and ifb interfaces in combination with a qdisc that splits GSO packets. This happens because at the time skb_segment() is called, network_header will point to the inner header, throwing off the calculation in skb_reset_mac_len(). The network_header is subsequently adjust by the outer IP gso_segment handlers, but they don't set the mac_len. Fix this by adding skb_reset_mac_len() calls to both the IPv4 and IPv6 gso_segment handlers, after they modify the network_header. Many thanks to Eric Dumazet for his help in identifying the cause of the bug. Acked-by: Dave Taht Reviewed-by: Eric Dumazet Signed-off-by: Toke Høiland-Jørgensen --- v2: - Properly credit Eric for his help - Add review and ack tags net/ipv4/af_inet.c | 1 + net/ipv6/ip6_offload.c | 1 + 2 files changed, 2 insertions(+) diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 20fda8fb8ffd..1fbe2f815474 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1377,6 +1377,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb, if (encap) skb_reset_inner_headers(skb); skb->network_header = (u8 *)iph - skb->head; + skb_reset_mac_len(skb); } while ((skb = skb->next)); out: diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c index 37ff4805b20c..c7e495f12011 100644 --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -115,6 +115,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb, payload_len = skb->len - nhoff - sizeof(*ipv6h); ipv6h->payload_len = htons(payload_len); skb->network_header = (u8 *)ipv6h - skb->head; + skb_reset_mac_len(skb); if (udpfrag) { int err = ip6_find_1stfragopt(skb, &prevhdr); -- 2.18.0