Date:	Thu, 10 Nov 2011 07:24:45 -0800
From:	"Guy, Wey-Yi" <wey-yi.w.guy@...el.com>
To:	Stanislaw Gruszka <sgruszka@...hat.com>
Cc:	Tomáš Janoušek <tomi@...i.cz>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>
Subject: Re: iwlagn: memory corruption with WPA enterprise

On Thu, 2011-11-10 at 08:07 -0800, Stanislaw Gruszka wrote:
> On Thu, Nov 10, 2011 at 01:53:47PM +0100, Tomáš Janoušek wrote:
> > > If "dmesg | grep corrupt" will show "Setting corrupt debug order to 1"
> > > patches are in use. Anyway I need to test the patches locally, to see
> > > if they work as expected, perhaps exception is generated but call-trace
> > > is not printed.
> > 
> > It does say that, yes.
> 
> I tested patches. They generate call-trace and make kernel panic when I
> wrote at random address from user address space. However to make kernel
> panic, we should keep as much as possible free memory, otherwise bad code
> corrupt not-protected data. In other words, when you run memory intensive
> application, corruption may happen on valid data.  So to catch the bug,
> you should just use network, and perhaps stress up cpu i.e: by this bash
> command:
> 
> while true; do : ; done 
> 
> Please also configure CONFIG_DEBUG_SET_MODULE_RONX=y, it protect modules
> text/read-only memory against corruption.
> 
> > > Is this happen only with "Intel Corporation Centrino Advanced-N 6205" or
> > > with some other adapters?
> > 
> > I don't have any other iwlwifi adapters, so I wouldn't know. The people in
> > that Ubuntu bugreport have exactly that card as well, but in another notebook.
> > And they claim it works in newer Ubuntu, but I am running latest kernels with
> > latest uCode, so I'm out of ideas what else could be wrong.
> 
> That's good hint for Intel folks. Would be ideal if any developer could
> reproduce that. I do not have this exact adapter model.
> 
> > > > Perhaps it would be cheaper to just get another card in that case.
> > > > :-)
> > >
> > > That will left issue unresolved :-(
> > 
> > Yeah, but considering how few people report this, I'm starting to feel that it
> > might in fact be a hardware issue.
> 
> It's possible, but I don think so. In my practice, majority of corruption
> problems was caused by software. All true hardware corruptions I meet, was on
> development boards, many months before they went into production.
> 
> > (We've got a lot of Lenovos here, mostly T520 and T420s, most of them running
> > Fedora, and nobody has reported memory corruption problems.
> 
> Are there any others with 6205? If not that would confirm issue is
> related with that model.

We try very hard on 6205 but can not reproduce this issue, I agree with
Stanislaw the memory corruption is most likely a sw problem.
1. please try older kernel, and possible bisect the kernel
2. could you provide your system information (model, CPU, memory,
graphic, ...), also the OS/kernel version and .config file. not sure we
have the similar system available, but I will like to see if there
anything stand out.

Thanks
Wey

> 
> > Perhaps I should try to connect to this WPA Enterprise using Windows and see
> > if anything goes wrong. However, I have no clue as to what shall I do to
> > reproduce the issue in Windows.)
> 
> You may first try some older kernel as Wey suggested, i.e. 2.6.38.
> 



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