[Xen-devel] Re: [PATCH 09/12] Fix possible NULL pointer dereference in print_IO_APIC

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 18 May 2010, Jeremy Fitzhardinge wrote:
> On 05/18/2010 03:23 AM, Stefano Stabellini wrote:
> > Make sure chip_data is not NULL before accessing it.
> >   
> 
> You should clarify under what circumstances it can be legitimately NULL.
> 
> 

The VIRQ_TIMER handler and virq handlers in general don't have any
chip_data.


> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > ---
> >  arch/x86/kernel/apic/io_apic.c |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> > index eb2789c..c64499c 100644
> > --- a/arch/x86/kernel/apic/io_apic.c
> > +++ b/arch/x86/kernel/apic/io_apic.c
> > @@ -1732,6 +1732,8 @@ __apicdebuginit(void) print_IO_APIC(void)
> >             struct irq_pin_list *entry;
> >  
> >             cfg = desc->chip_data;
> > +           if (!cfg)
> > +                   continue;
> >             entry = cfg->irq_2_pin;
> >             if (!entry)
> >                     continue;
> >   
> 

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