Re: Oops in ACPI with git latest

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Friday, 24 of October 2008, Jesse Barnes wrote:
> So who wants to send me a final patch for this?

I already did: http://marc.info/?l=linux-kernel&m=122484871717023&w=4
but I can remove the "!output.pointer || " if you prefer. :-)

Thanks,
Rafael


> On Friday, October 24, 2008 7:57 am Moore, Robert wrote:
> > Since acpi_evaluate_object doesn't set the pointer value, it may be simply
> > random.
> >
> > >-----Original Message-----
> > >From: Rafael J. Wysocki [mailto:rjw@sisk.pl]
> > >Sent: Thursday, October 23, 2008 11:57 PM
> > >To: James Bottomley; Jesse Barnes
> > >Cc: Moore, Robert; linux-acpi@vger.kernel.org; linux-kernel; Len Brown
> > >Subject: Re: Oops in ACPI with git latest
> > >
> > >On Friday, 24 of October 2008, James Bottomley wrote:
> > >> On Thu, 2008-10-23 at 15:34 -0700, Moore, Robert wrote:
> > >> > +	if (!output.pointer)
> > >> > +		return AE_NULL_OBJECT;
> > >> > +
> > >> >
> > >> > This probably won't work. acpi_evaluate_object currently doesn't touch
> > >
> > >the pointer parameter if there is no return value, it only sets the length
> > >to zero.
> > >
> > >> Actually, it does.
> > >
> > >Well, this was the only candidate for a NULL pointer dereference, so I'd
> > > be surprised if it didn't. :-)
> > >
> > >> > So, you might try this:
> > >> >
> > >> > +	if (!output.length)
> > >> > +		return AE_NULL_OBJECT;
> > >> > +
> > >
> > >Still, I'd expect the AML interpreter to return error code in this case.
> > >
> > >> This also works.
> > >
> > >Why don't we make it extra safe, then. ;-)
> > >
> > >---
> > >From: Rafael J. Wysocki <rjw@sisk.pl>
> > >Subject: Prevent acpi_osc_run from using NULL objects
> > >
> > >Check if the object returned by acpi_evaluate_object() in
> > >acpi_run_osc() is not NULL.
> > >
> > >Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > >---
> > > drivers/pci/pci-acpi.c |    3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > >Index: linux-2.6/drivers/pci/pci-acpi.c
> > >===================================================================
> > >--- linux-2.6.orig/drivers/pci/pci-acpi.c
> > >+++ linux-2.6/drivers/pci/pci-acpi.c
> > >@@ -83,6 +83,9 @@ static acpi_status acpi_run_osc(acpi_han
> > > 	if (ACPI_FAILURE(status))
> > > 		return status;
> > >
> > >+	if (!output.pointer || !output.length)
> > >+		return AE_NULL_OBJECT;
> > >+
> > > 	out_obj = output.pointer;
> > > 	if (out_obj->type != ACPI_TYPE_BUFFER) {
> > > 		printk(KERN_DEBUG "Evaluate _OSC returns wrong type\n");
> >
> > --
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