netdev - Re: [PATCH net] net: ep93xx_eth: Do not crash unloading module

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Message-Id: <20161205.153602.1770726597007697695.davem@davemloft.net>
Date:   Mon, 05 Dec 2016 15:36:02 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     f.fainelli@...il.com
Cc:     netdev@...r.kernel.org, hsweeten@...ionengravers.com
Subject: Re: [PATCH net] net: ep93xx_eth: Do not crash unloading module

From: Florian Fainelli <f.fainelli@...il.com>
Date: Sun,  4 Dec 2016 19:22:05 -0800

> When we unload the ep93xx_eth, whether we have opened the network
> interface or not, we will either hit a kernel paging request error, or a
> simple NULL pointer de-reference because:
> 
> - if ep93xx_open has been called, we have created a valid DMA mapping
>   for ep->descs, when we call ep93xx_stop, we also call
>   ep93xx_free_buffers, ep->descs now has a stale value
> 
> - if ep93xx_open has not been called, we have a NULL pointer for
>   ep->descs, so performing any operation against that address just won't
>   work
> 
> Fix this by adding a NULL pointer check for ep->descs which means that
> ep93xx_free_buffers() was able to successfully tear down the descriptors
> and free the DMA cookie as well.
> 
> Fixes: 1d22e05df818 ("[PATCH] Cirrus Logic ep93xx ethernet driver")
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>

Applied, thanks Florian.