Subject: Re: [PATCH stable 4.4 7/9] tcp: detect malicious patterns in tcp_collapse_ofo_queue()

From: Greg KH <[email-masked]>
Date: Wed, 15 Aug 2018 15:19:13 +0200

On Wed, Aug 15, 2018 at 09:21:06PM +0800, Mao Wenan wrote:
> From: Eric Dumazet <[email-masked]>
> 
> [ Upstream commit 3d4bf93ac12003f9b8e1e2de37fe27983deebdcf ]
> 
> In case an attacker feeds tiny packets completely out of order,
> tcp_collapse_ofo_queue() might scan the whole rb-tree, performing
> expensive copies, but not changing socket memory usage at all.
> 
> 1) Do not attempt to collapse tiny skbs.
> 2) Add logic to exit early when too many tiny skbs are detected.
> 
> We prefer not doing aggressive collapsing (which copies packets)
> for pathological flows, and revert to tcp_prune_ofo_queue() which
> will be less expensive.
> 
> In the future, we might add the possibility of terminating flows
> that are proven to be malicious.
> 
> Signed-off-by: Eric Dumazet <[email-masked]>
> Acked-by: Soheil Hassas Yeganeh <[email-masked]>
> Signed-off-by: David S. Miller <[email-masked]>
> Signed-off-by: Greg Kroah-Hartman <[email-masked]>
> Signed-off-by: root <[email-masked]>

signed off by from "root"?  :)

And why are you adding the patch back after removing it?

thanks,

greg k-h