[2.6 patch] dvb_frontend_ioctl(): fix check-after-use

[2.6 patch] dvb_frontend_ioctl(): fix check-after-use

[Adrian Bunk]

The Coverity checker spotted that we have already oops'ed if "fe" was NULL.

Since "fe" being NULL seems impossible at this point this patch removes 
the NULL check.

Signed-off-by: Adrian Bunk <bunk@stusta.de>

---
--- linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c.old	2007-07-29 21:41:56.000000000 +0200
+++ linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c	2007-07-29 21:42:16.000000000 +0200
@@ -706,11 +706,11 @@ static int dvb_frontend_ioctl(struct ino
 	struct dvb_frontend_private *fepriv = fe->frontend_priv;
 	int err = -EOPNOTSUPP;
 
 	dprintk ("%s\n", __FUNCTION__);
 
-	if (!fe || fepriv->exit)
+	if (fepriv->exit)
 		return -ENODEV;
 
 	if ((file->f_flags & O_ACCMODE) == O_RDONLY &&
 	    (_IOC_DIR(cmd) != _IOC_READ || cmd == FE_GET_EVENT ||
 	     cmd == FE_DISEQC_RECV_SLAVE_REPLY))

Re: [2.6 patch] dvb_frontend_ioctl(): fix check-after-use

[Manu Abraham]

On 7/31/07, Adrian Bunk <bunk@stusta.de> wrote:
> The Coverity checker spotted that we have already oops'ed if "fe" was NULL.
>
> Since "fe" being NULL seems impossible at this point this patch removes
> the NULL check.
>
> Signed-off-by: Adrian Bunk <bunk@stusta.de>
>
> ---
> --- linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c.old  2007-07-29 21:41:56.000000000 +0200
> +++ linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c      2007-07-29 21:42:16.000000000 +0200
> @@ -706,11 +706,11 @@ static int dvb_frontend_ioctl(struct ino
>         struct dvb_frontend_private *fepriv = fe->frontend_priv;
>         int err = -EOPNOTSUPP;
>
>         dprintk ("%s\n", __FUNCTION__);
>
> -       if (!fe || fepriv->exit)
> +       if (fepriv->exit)
>                 return -ENODEV;
>
>         if ((file->f_flags & O_ACCMODE) == O_RDONLY &&
>             (_IOC_DIR(cmd) != _IOC_READ || cmd == FE_GET_EVENT ||
>              cmd == FE_DISEQC_RECV_SLAVE_REPLY))
>
> -

Acked-by: Manu Abraham <manu@linuxtv.org>

Re: [v4l-dvb-maintainer] [2.6 patch] dvb_frontend_ioctl(): fix check-after-use

[Markus Rechberger]

On 8/1/07, Manu Abraham <abraham.manu@gmail.com> wrote:
> On 7/31/07, Adrian Bunk <bunk@stusta.de> wrote:
> > The Coverity checker spotted that we have already oops'ed if "fe" was
> NULL.
> >
> > Since "fe" being NULL seems impossible at this point this patch removes
> > the NULL check.
> >
> > Signed-off-by: Adrian Bunk <bunk@stusta.de>
> >
> > ---
> > --- linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c.old
> 2007-07-29 21:41:56.000000000 +0200
> > +++ linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c
> 2007-07-29 21:42:16.000000000 +0200
> > @@ -706,11 +706,11 @@ static int dvb_frontend_ioctl(struct ino
> >         struct dvb_frontend_private *fepriv = fe->frontend_priv;
> >         int err = -EOPNOTSUPP;
> >
> >         dprintk ("%s\n", __FUNCTION__);
> >
> > -       if (!fe || fepriv->exit)
> > +       if (fepriv->exit)
> >                 return -ENODEV;
> >
> >         if ((file->f_flags & O_ACCMODE) == O_RDONLY &&
> >             (_IOC_DIR(cmd) != _IOC_READ || cmd == FE_GET_EVENT ||
> >              cmd == FE_DISEQC_RECV_SLAVE_REPLY))
> >
> > -
>
> Acked-by: Manu Abraham <manu@linuxtv.org>
>

This issue has been known for a while including some other problems at
that part.

http://article.gmane.org/gmane.linux.drivers.dvb/35351/match=patch+dvb_net+hotplugging+support

this includes a link where this and more got discussed in May.

Markus

Re: [v4l-dvb-maintainer] [2.6 patch] dvb_frontend_ioctl(): fix check-after-use

[Trent Piepho]

On Fri, 10 Aug 2007, Markus Rechberger wrote:
> On 8/1/07, Manu Abraham <abraham.manu@gmail.com> wrote:
> > On 7/31/07, Adrian Bunk <bunk@stusta.de> wrote:
> > > The Coverity checker spotted that we have already oops'ed if "fe" was
> > NULL.
> > >
> > > --- linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c.old
> > > +++ linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c
> > > @@ -706,11 +706,11 @@ static int dvb_frontend_ioctl(struct ino
> > > -       if (!fe || fepriv->exit)
> > > +       if (fepriv->exit)
> > >                 return -ENODEV;
>
> This issue has been known for a while including some other problems at
> that part.
>
> http://article.gmane.org/gmane.linux.drivers.dvb/35351/match=patch+dvb_net+hotplugging+support
>
> this includes a link where this and more got discussed in May.

For dvb_net_close, I like the patch I already posted better.  To fix the
check-after-use, it's not "use" part that's the problem, it's the "check" part
that isn't necessary.

I traced the dvb-net code, http://article.gmane.org/gmane.linux.kernel/543689,
and I'm sure that dvbdev can't be NULL.

My patch also deletes a few pieces of duplicated code by calling
dvb_generic_release().

The only problem is that practically no one uses dvb-net, so it's very hard to
test these patches.

In all the dvb code, were is the locking for device open and release?  I don't
see it.  What is preventing two threads from trying to open and/or close the
same dvb device at the same time?

Re: [v4l-dvb-maintainer] [2.6 patch] dvb_frontend_ioctl(): fix check-after-use

[Markus Rechberger]

On 8/11/07, Trent Piepho <xyzzy@speakeasy.org> wrote:
> On Fri, 10 Aug 2007, Markus Rechberger wrote:
> > On 8/1/07, Manu Abraham <abraham.manu@gmail.com> wrote:
> > > On 7/31/07, Adrian Bunk <bunk@stusta.de> wrote:
> > > > The Coverity checker spotted that we have already oops'ed if "fe" was
> > > NULL.
> > > >
> > > > --- linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c.old
> > > > +++ linux-2.6.23-rc1-mm1/drivers/media/dvb/dvb-core/dvb_frontend.c
> > > > @@ -706,11 +706,11 @@ static int dvb_frontend_ioctl(struct ino
> > > > -       if (!fe || fepriv->exit)
> > > > +       if (fepriv->exit)
> > > >                 return -ENODEV;
> >
> > This issue has been known for a while including some other problems at
> > that part.
> >
> >
> http://article.gmane.org/gmane.linux.drivers.dvb/35351/match=patch+dvb_net+hotplugging+support
> >
> > this includes a link where this and more got discussed in May.
>
> For dvb_net_close, I like the patch I already posted better.  To fix the
> check-after-use, it's not "use" part that's the problem, it's the "check"
> part
> that isn't necessary.
>
> I traced the dvb-net code,
> http://article.gmane.org/gmane.linux.kernel/543689,
> and I'm sure that dvbdev can't be NULL.
>
> My patch also deletes a few pieces of duplicated code by calling
> dvb_generic_release().
>
> The only problem is that practically no one uses dvb-net, so it's very hard
> to
> test these patches.
>

I didn't see this patch, it would be fine if it would get applied.

> In all the dvb code, were is the locking for device open and release?  I
> don't
> see it.  What is preventing two threads from trying to open and/or close the
> same dvb device at the same time?
>

Haven't looked at that yet, since I moreover work to get the em28xx
driver included now.

Markus