From: Sowmini Varadhan <sowmini.varadhan@oracle•com>
To: "Duyck, Alexander H" <alexander.h.duyck@intel•com>
Cc: "netdev@vger•kernel.org" <netdev@vger•kernel.org>
Subject: Re: bug in ixgbe_atr
Date: Thu, 13 Oct 2016 20:48:31 -0700 [thread overview]
Message-ID: <20161014034831.GC14253@oracle.com> (raw)
In-Reply-To: <B1C1DF2ACD01FD4881736AA51731BAB2A0DDE3@ORSMSX107.amr.corp.intel.com>
On (10/14/16 02:06), Duyck, Alexander H wrote:
> > + case ETH_P_IP:
> > + skb_header_pointer(skb, ETH_HLEN, sizeof (struct iphdr),
> > + &ip_hdr);
> > /* access ihl as u8 to avoid unaligned access on ia64 */
> > - hlen = (hdr.network[0] & 0x0F) << 2;
> > - l4_proto = hdr.ipv4->protocol;
> > + hlen = ip_hdr.ipv4.ihl << 2;
> > + l4_proto = ip_hdr.ipv4.protocol;
> > break;
:
> The problem is this will break other stuff, for example I have seen
> the ihl access actually cause problems with unaligned accesses as some
> architectures decide to pull it as a u32 and then mask it.
Yes, I noticed that u8 comment for ia64.. if that's the only issue
here, we could just reset hdr.network to &ip_hdr..
However, I suspect the above patch is probably not going to work for
the vlan case (it was just a first-pass hack)
> My advice would be to keep this simple. Add a check to make sure we
> have room for at least skb_headlen(skb) - 40 >= hrd.raw - skb->data.
I don't parse that- the hdr union in ixgbe_atr doesnt have a ->raw
field. Can you explain?
> Messing with the protocol bits will break stuff since there is support
> for tunneling also floating around in here now.
>
> I believe we are planning on dropping this code in favor of
> ndo_rx_flow_steer in the future. If we do that then the whole problem
> becomes moot.
Dropping it is fine with me I guess - maybe just return, if the
skb_headlen() doesnt have enough bytes for a network header,
i.e., skb_headlen is at least ETH_HLEN + sizeof (struct iphdr) for
ETH_P_IP, or ETH_HLEN + sizeof (struct ipv6hdr) for ETH_P_IPV6?
--Sowmini
next prev parent reply other threads:[~2016-10-14 3:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-14 1:44 bug in ixgbe_atr Sowmini Varadhan
2016-10-14 2:06 ` Duyck, Alexander H
2016-10-14 3:48 ` Sowmini Varadhan [this message]
2016-10-14 16:09 ` Duyck, Alexander H
2016-10-14 23:00 ` Sowmini Varadhan
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