netdev - Re: IPv6 xfrm GSO fragmentation bug

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Date:	Mon, 31 Aug 2015 15:35:26 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Steffen Klassert <steffen.klassert@...unet.com>
Cc:	netdev@...r.kernel.org
Subject: Re: IPv6 xfrm GSO fragmentation bug

On Mon, Aug 31, 2015 at 09:19:16AM +0200, Steffen Klassert wrote:
>
> As far as I remember, this was to catch local message size
> errors before __xfrm6_output calls ip6_fragment which would
> use icmpv6_send for the error notification. IPv4 does not do
> fragmentation in the xfrm4_output functions, so this mtu
> check was not needed there.
> 
> I think just adding the gso checks should be fine.

I see where the bug came from.  Indeed IPv6 does do fragmentation
but only for tunnel mode.  While your patch added a check that also
affected transport mode.  So in addition to the GSO fix we should
also make the MTU check conditional to tunnel mode.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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