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From: James Lee <lizheng043@gmail.com>
Date: Tue, 19 Mar 2024 17:42:34 +0800
Message-ID: <CAPCnf4z0gp47TkxP+PFw3bd_Weh7=jn9Q2t-z6QB654Ckc36Pg@mail.gmail.com>
Subject: Re: [EXTERNAL] Re: [PATCH] neighbour: guarantee the localhost
 connections be established successfully even the ARP table is full
To: Ratheesh Kannoth <rkannoth@marvell.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, 
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>, "nhorman@tuxdriver.com" <nhorman@tuxdriver.com>, 
	"davem@davemloft.net" <davem@davemloft.net>, "jmorris@namei.org" <jmorris@namei.org>, 
	"James.Z.Li@dell.com" <James.Z.Li@dell.com>
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It's not an issue, the loopback device can only be created by kernel
itself, loopback neigh entry also can only be created by kernel, one
loopback neigh for ipv4 ,one for ipv6, impossible that the num of
loopback neigh entries exceeds 2.

Ratheesh Kannoth <rkannoth@marvell.com> =E4=BA=8E2024=E5=B9=B43=E6=9C=8818=
=E6=97=A5=E5=91=A8=E4=B8=80 23:36=E5=86=99=E9=81=93=EF=BC=9A
>
> > From: James Lee <lizheng043@gmail.com>
> > Sent: Monday, March 18, 2024 2:09 PM
> > To: Ratheesh Kannoth <rkannoth@marvell.com>
> > Cc: linux-kernel@vger.kernel.org; netdev@vger.kernel.org;
> > nhorman@tuxdriver.com; davem@davemloft.net; jmorris@namei.org;
> > James.Z.Li@dell.com
> > Subject: [EXTERNAL] Re: [PATCH] neighbour: guarantee the localhost
> > connections be established successfully even the ARP table is full
> >
> > Prioritize security for external emails: Confirm sender and content saf=
ety
> > before clicking links or opening attachments
> >
> > ----------------------------------------------------------------------
> > loopback neigh is a special device in the neighbour system which is use=
d by all
> > local communications and state is NUD_NOARP.
> > Any setting value of gc_thresh3 might encounter arp table be full, manu=
ally
> > increasing gc_thresh3 can resolve this issue for every time, but we hop=
e this
> > issue automatically be resolved in Linux kernel for all local communica=
tions
> > whenever ARP table is full, rather than manually operation as a workaro=
und.
>
> Issue is , these are dynamic entries which cannot be removed by gc.  And =
there is no
> Threshold applicable on it.  I feel like, this may be exploited.
>