Since acpi_evaluate_object doesn't set the pointer value, it may be simply random. >-----Original Message----- >From: Rafael J. Wysocki [mailto:rjw@xxxxxxx] >Sent: Thursday, October 23, 2008 11:57 PM >To: James Bottomley; Jesse Barnes >Cc: Moore, Robert; linux-acpi@xxxxxxxxxxxxxxx; 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@xxxxxxx> >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@xxxxxxx> >--- > 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"); -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
