From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH net] gso: Validate assumption of frag_list segementation Date: Wed, 19 Apr 2017 21:26:07 +0300 Message-ID: <20170419182607.2342-1-ilant@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , Alexander Duyck , Eric Dumazet , Steffen Klassert , Boris Pismenny , Ilya Lesokhin , Ilan Tayari To: David Miller Return-path: Received: from mail-he1eur01on0044.outbound.protection.outlook.com ([104.47.0.44]:23053 "EHLO EUR01-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1030686AbdDSS0V (ORCPT ); Wed, 19 Apr 2017 14:26:21 -0400 Sender: netdev-owner@vger.kernel.org List-ID: From: Ilan Tayari Commit 07b26c9454a2 ("gso: Support partial splitting at the frag_list pointer") assumes that all SKBs in a frag_list (except maybe the last one) contain the same amount of GSO payload. This assumption is not always correct, resulting in the following warning message in the log: skb_segment: too many frags For example, mlx5 driver in Striding RQ mode creates some RX SKBs with one frag, and some with 2 frags. After GRO, the frag_list SKBs end up having different amounts of payload. If this frag_list SKB is then forwarded, the aforementioned assumption is violated. Validate the assumption, and fall back to software GSO if it not true. Change-Id: Ia03983f4a47b6534dd987d7a2aad96d54d46d212 Fixes: 07b26c9454a2 ("gso: Support partial splitting at the frag_list pointer") Signed-off-by: Ilan Tayari Signed-off-by: Ilya Lesokhin --- net/core/skbuff.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 35c1e2460206..f86bf69cfb8d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3082,22 +3082,32 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, if (sg && csum && (mss != GSO_BY_FRAGS)) { if (!(features & NETIF_F_GSO_PARTIAL)) { struct sk_buff *iter; + unsigned int frag_len; if (!list_skb || !net_gso_ok(features, skb_shinfo(head_skb)->gso_type)) goto normal; - /* Split the buffer at the frag_list pointer. - * This is based on the assumption that all - * buffers in the chain excluding the last - * containing the same amount of data. + /* If we get here then all the required + * GSO features except frag_list are supported. + * Try to split the SKB to multiple GSO SKBs + * with no frag_list. + * Currently we can do that only when the buffers don't + * have a linear part and all the buffers except + * the last are of the same length. */ + frag_len = list_skb->len; skb_walk_frags(head_skb, iter) { + if (frag_len != iter->len && iter->next) + goto normal; if (skb_headlen(iter)) goto normal; len -= iter->len; } + + if (len != frag_len) + goto normal; } /* GSO partial only requires that we trim off any excess that -- 2.11.0