netdev - Re: [PATCH 07/16] esp4: Reorganize esp

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Message-ID: <20170426120643.GV2649@secunet.com>
Date:   Wed, 26 Apr 2017 14:06:43 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Ilan Tayari <ilant@...lanox.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 07/16] esp4: Reorganize esp_output

On Wed, Apr 26, 2017 at 11:52:47AM +0000, Ilan Tayari wrote:
> 
> esp_output_head() might do an skb_cow, which then invalidates the esp.esph pointer and causes a crash later on.
> I would expect the ip_esp_hdr() call to be after the esp_output_head() call.
> 
> But it seems like this pointer was saved here around the call to esp_output_head() on purpose.
> Is that really so? 

Yes, it is needed for udpencap, this might also change esp.esph pointer.
I guess this needs to be done also if skb_cow invalidates the esp.esph
pointer.

> 
> Also, esp6/esp6_offload don't make use of esp_info.esph
> Only esp_output_tail() uses it, and could have done everything it does without it.
> So maybe it's un-needed?

IPv6 does not have udpencap, so it might be not needed there.

> 
> I am still testing a fix patch for the crash, there may be also something similar on the RX path, though.

Ok, thanks!