netdev - Re: Regression from "ipv4: Cache ip_error() routes even when not forwarding."

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Date:	Sat, 17 Jan 2015 10:25:38 +0200 (EET)
From:	Julian Anastasov <ja@....bg>
To:	Francesco Ruggeri <fruggeri@...stanetworks.com>
cc:	fruggeri@...sta.com, davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: Regression from "ipv4: Cache ip_error() routes even when not
 forwarding."


	Hello,

On Fri, 16 Jan 2015, Francesco Ruggeri wrote:

> Commit 251da413("ipv4: Cache ip_error() routes even when not forwarding."),
> later slightly modified by cd0f0b95("ipv4: distinguish EHOSTUNREACH from
> the ENETUNREACH"), introduced a regression where an ip_error route is cached
> when an ARP request is received on a non-forwarding non matching interface,
> and it affects later legitimate packets for the same destination even if
> coming over different interfaces.
> Attached are two scripts that show the problem. The first one does basic
> forwarding, and the second one does proxy arp.
> In both cases a dummy interface is created for the sole purpose of receiving
> an ARP request that results in the ip_error route to be cached. The offending
> ARP request is generated by using a 'ping -c 1' (commented out in the scripts).
> Verified in 3.16 build.

	3.16? Just in case, can you check if this
fix from 3.18 helps:

commit fa19c2b050ab5254326f5fc07096dd3c6a8d5d58
Author: Nicolas Cavallari <nicolas.cavallari@...en-communications.fr>
Date:   Thu Oct 30 10:09:53 2014 +0100

    ipv4: Do not cache routing failures due to disabled forwarding.

Regards

--
Julian Anastasov <ja@....bg>
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