netdev - Re: [PATCH net] r8152: Fix broken RX checksums.

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Date:   Fri, 4 Nov 2016 09:50:20 -0400
From:   Mark Lord <mlord@...ox.com>
To:     Hayes Wang <hayeswang@...ltek.com>,
        David Miller <davem@...emloft.net>
Cc:     nic_swsd <nic_swsd@...ltek.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] r8152: Fix broken RX checksums.

Yeah, the device or driver is definitely getting confused with rx_desc structures.
I added code to check for unlikely rx_desc values, and it found this for starters:

rx_desc: 00480801 00480401 00480001 0048fc00 0048f800 0048f400 pkt_len=2045
rx_data: 00 f0 48 00 00 ec 48 00 00 e8 48 00 00 e4 48 00 00 e0 48 00 00 dc 48 00 00 d8 48 00 00 d4 48 00
rx_data: 00 d0 48 00 00 cc 48 00 00 c8 48 00 00 c4 48 00 00 c0 48 00 00 bc 48 00 00 b8 48 00 00 b4 48 00
rx_data: 00 b0 48 00 00 ac 48 00 00 01 00 00 81 ed 00 00 00 01 00 00 00 00 00 00 00 00 00 02 4d ac 00 00
rx_data: 10 00 ff ff ff ff 00 00 01 28 83 d6 ff 6d 00 20 25 b1 58 1b 68 ff 00 05 20 01 56 41 17 35 00 00
...

The MTU/MRU on this link is the standard 1500 bytes, so a pkt_len of 2045 isn't valid here.
And the rx_desc values look an awful lot like the rx_data values that follow it.

There's definitely more broken here than just TCP RX checksums.

-ml