This is a note to let you know that I've just added the patch titled gso: Validate assumption of frag_list segementation to the 4.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: gso-validate-assumption-of-frag_list-segementation.patch and it can be found in the queue-4.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sat Apr 29 08:22:40 CEST 2017 From: Ilan Tayari <ilant@xxxxxxxxxxxx> Date: Wed, 19 Apr 2017 21:26:07 +0300 Subject: gso: Validate assumption of frag_list segementation From: Ilan Tayari <ilant@xxxxxxxxxxxx> [ Upstream commit 43170c4e0ba709c79130c3fe5a41e66279950cd0 ] 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 <ilant@xxxxxxxxxxxx> Signed-off-by: Ilya Lesokhin <ilyal@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/core/skbuff.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3078,22 +3078,32 @@ struct sk_buff *skb_segment(struct sk_bu 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 Patches currently in stable-queue which might be from ilant@xxxxxxxxxxxx are queue-4.10/gso-validate-assumption-of-frag_list-segementation.patch queue-4.10/net-mlx5e-fix-ethtool_grxclsrlall-handling.patch