netdev - Re: Need help debugging memory corruption

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Mon, 5 May 2008 07:50:40 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Jay Cliburn <jacliburn@...lsouth.net>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	Chris Snook <csnook@...hat.com>
Subject: Re: Need help debugging memory corruption

On Mon, May 05, 2008 at 07:27:34AM +0000, Jarek Poplawski wrote:
> On Sun, May 04, 2008 at 02:55:29PM -0500, Jay Cliburn wrote:
> > On Sun, 04 May 2008 16:55:08 +0200
> > Jarek Poplawski <jarkao2@...il.com> wrote:
> > 
> > > Jarek Poplawski wrote, On 05/04/2008 04:24 PM:
> > > ...
> > > 
> > > > I'm definitely with less experience, so I wonder why it can't be
> > > > a simple race between atl1_clean_rx_ring() and something (maybe even
> > > > pending atl1_intr_rx()) on the other cpu writing skb while kfreeing?
> > > 
> > > 
> > > Hmm... atl1_intr_rx() looks impossible, so atl1_alloc_rx_buffers()?
> > 
> > I booted with nosmp and the bug is *much* harder to hit, but I still
> > hit it once out of about 10 tries.  Does the fact that I hit it once
> > using nosmp disprove the race theory?
> 
> Probably not: I don't know how about preemption model, but especially
> some maybe unkilled timers/watchdogs or workqueues could be considered.
> Of course this idea looks very unprobable (should happen with less
> than 4GB too), but should be quite easy to verify by adding some
> temporary spinlocks around these rx ring operations?

Hmm#2... Of course for testing without smp disabling local irqs should
be enough. BTW... since this check is done during __free_slab it seems
such a corruption could take place before this closing, so maybe this
atl1_intr_rx() should be considered in these races yet...

Jarek P.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html