linux-kernel - Re: dvb shared datastructure bug?

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Date:	Tue, 13 Feb 2007 15:14:23 +0400
From:	"Manu Abraham" <abraham.manu@...il.com>
To:	"Marcel Siegert" <mws@...uxtv.org>
Cc:	"Arjan van de Ven" <arjan@...radead.org>, mchehab@...radead.org,
	v4l-dvb-maintainer@...uxtv.org, linux-kernel@...r.kernel.org
Subject: Re: dvb shared datastructure bug?

On 2/13/07, Marcel Siegert <mws@...uxtv.org> wrote:
> On Tuesday 13 February 2007, Arjan van de Ven wrote:
> > Hi,
> >
> > while working on the last pieces of the file_ops constantification, DVB
> > is the small village in France that is holding the Romans at bay... but
> > I think I found the final flaw in it now:
> >
> >        *pdvbdev = dvbdev = kmalloc(sizeof(struct dvb_device), GFP_KERNEL);
> >
> >         if (!dvbdev) {
> >                 mutex_unlock(&dvbdev_register_lock);
> >                 return -ENOMEM;
> >         }
> >
> >         memcpy(dvbdev, template, sizeof(struct dvb_device));
> >         dvbdev->type = type;
> >         dvbdev->id = id;
> >         dvbdev->adapter = adap;
> >         dvbdev->priv = priv;
> >
> >         dvbdev->fops->owner = adap->module;
> >
> >
> > this is the place in DVB that is writing to a struct file_operations.
> > But as with almost all such cases in the kernel, this one is buggy:
> > While the code nicely copies a template dvbdev, that template only has a
> > pointer to a *shared* fops struct, the copy doesn't help that. So this
> > code is overwriting the fops owner field for ALL active devices, not
> > just the ones the copy of the template is for....
> >
> > I'm lost in the maze of this part of DVB (it seems to have some magic
> > potion to resist me) but I was hoping some of the local citizens could
> > take a look at this buglet...
> >
> > Greetings,
> >     Arjan van de Ven
>
> hi arjan,
> thanks for pointing out this issue.
>
> attached find a patch that fixes the problem.
>
> @mauro - please pull changeset a7ac92d208fe
>    dvbdev: fix illegal re-usage of fileoperations struct
>
> from  http://www.linuxtv.org/hg/~mws/v4l-dvb-fixtree
>

Ack'd-by: Manu Abraham <manu@...uxtv.org>
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