netdev - Re: [PATCH net] ibmvnic: Clean RX pools only during a hard reset

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Message-Id: <20180219.143057.1751495030105842591.davem@davemloft.net>
Date:   Mon, 19 Feb 2018 14:30:57 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     tlfalcon@...ux.vnet.ibm.com
Cc:     netdev@...r.kernel.org, nfont@...ux.vnet.ibm.com,
        jallen@...ux.vnet.ibm.com
Subject: Re: [PATCH net] ibmvnic: Clean RX pools only during a hard reset

From: Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>
Date: Mon, 19 Feb 2018 13:24:52 -0600

> Sorry, I should explain it better. It's not there is a double free.
> It's that the driver is receiving RX descriptors from the previous
> session for which socket buffers have been freed. The driver's
> polling routine tries to copy data to the socket buffer, but it's
> been freed, so it's trying to copy to a NULL pointer.

That's kinda hairy, is this resend of the old descriptors guaranteed
to always happen in this situation?

Maybe it's better to have some way for the RX descriptor receiving
path to detect this situation (is SKB slot NULL?) to handle the
problem there.

Thanks.