Subject: Re: [PATCH] net: gro: make sure skb->cb[] initial content has not to be zero

From: Timo Teras <[email-masked]>
Date: Fri, 16 May 2014 22:08:22 +0300

On Fri, 16 May 2014 11:34:37 -0700
Eric Dumazet <[email-masked]> wrote:

> From: Eric Dumazet <[email-masked]>
> 
> Starting from linux-3.13, GRO attempts to build full size skbs.
> 
> Problem is the commit assumed one particular field in skb->cb[]
> was clean, but it is not the case on some stacked devices.
> 
> Timo reported a crash in case traffic is decrypted before
> reaching a GRE device.
> 
> Fix this by initializing NAPI_GRO_CB(skb)->last at the right place,
> this also removes one conditional.
> 
> Thanks a lot to Timo for providing full reports and bisecting this.
> 
> Fixes: 8a29111c7ca6 ("net: gro: allow to build full sized skb")
> Bisected-by: Timo Teras <[email-masked]>
> Signed-off-by: Eric Dumazet <[email-masked]>
> ---
> Please Timo test this patch so that we confirm it fixes the bug for
> you.

Yes, everything looks green now! (The test case reproduced the crash
reliably and immediately. Now it's been up and working for more than
tens minutes already :)

Tested-by: Timo Teräs <[email-masked]>

Needless to say, this should go to 3.14-stable as well.

Thanks a lot Eric!