Re: [PATCH 2/2] media: omap3isp change to devm for resources

[Hans Verkuil]

On 16/12/16 13:19, Laurent Pinchart wrote:
> Hi Hans,
>
> On Friday 16 Dec 2016 12:39:49 Hans Verkuil wrote:
> > On 15/12/16 20:40, Shuah Khan wrote:
> > > Using devm resources that have external dependencies such as a dev
> > > for a file handler could result in devm resources getting released
> > > durin unbind while an application has the file open holding pointer
> > > to the devm resource. This results in use-after-free errors when the
> > > application exits.
> >
> > That's solving the wrong problem.
> >
> > The real problem is that when registering a video_device it should do
> > this:
> >
> > devnode->cdev.kobj.parent = &devnode->dev.kobj;
> >
> > (taken from cec-core.c)
> >
> > This will prevent isp->dev from being released as long as there is a
> > filehandle still open.
>
> But it won't be enough, devm_* resources are released at unbind time, not at
> device release time. Right after the unbind (.remove() for platform devices)
> handler returns, devm_kzalloc allocated memory goes away.

You're completely right, I keep forgetting about that.

Sorry for the noise.

	Hans

> > After that change I believe that this will work correctly, but this
> > has to be tested first!