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

[Greg KH <gregkh@linux-foundation.org>]

On Wed, Aug 15, 2018 at 09:21:06PM +0800, Mao Wenan wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> [ 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 <edumazet@google.com>
> Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: root <root@localhost.localdomain>

signed off by from "root"?  :)

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

thanks,

greg k-h