>> Still, I'd expect the AML interpreter to return error code in this case. We've just recently deployed a new module that validates the inputs and outputs for the predefined ACPI methods (Those that start with underscore). That is the source of these messages: > > ACPI Warning (nspredef-0252): \_SB_.PCI0._OSC: Parameter count mismatch - ASL declared 5, expected 4 [20080926] > > ACPI Error (nspredef-0163): \_SB_.PCI0._OSC: Missing expected return value [20080926] For the initial version of this module, we only output messages when the inputs and/or outputs don't match the requirements of the ACPI specification. We can change this to returning exceptions in the future. >-----Original Message----- >From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- >owner@xxxxxxxxxxxxxxx] On Behalf Of Rafael J. Wysocki >Sent: Friday, October 24, 2008 4:50 AM >To: James Bottomley; Jesse Barnes >Cc: Moore, Robert; linux-acpi@xxxxxxxxxxxxxxx; linux-kernel; Len Brown >Subject: [PATCH] Subject: Prevent acpi_run_osc from using NULL objects >(was: Re: Oops in ACPI with git latest) > >On Friday, 24 of October 2008, Rafael J. Wysocki wrote: >> 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 > >Ah, mistake in the subject. > >--- >From: Rafael J. Wysocki <rjw@xxxxxxx> >Subject: Prevent acpi_run_osc from using NULL objects > >Check if the object returned by acpi_evaluate_object() in >acpi_run_osc() is not NULL before using it. > >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 -- 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
