Re: [PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from ioremap_nocache

[Arvind Yadav]

Hi Matt,

Please Acknowledge this.

Regards
Arvind Yadav

On Monday 09 January 2017 02:30 PM, Marc Zyngier wrote:
> On 09/01/17 08:08, Arvind Yadav wrote:
> > Here, If ioremap_nocache will fail. It will return NULL.
> > Kernel can run into a NULL-pointer dereference.
> > This error check will avoid NULL pointer dereference.
> >
> > Signed-off-by: Arvind Yadav <arvind.yadav.cs@xxxxxxxxx>
> > ---
> >   drivers/irqchip/irq-mips-gic.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
> > index c01c09e..eeea2e8 100644
> > --- a/drivers/irqchip/irq-mips-gic.c
> > +++ b/drivers/irqchip/irq-mips-gic.c
> > @@ -979,6 +979,8 @@ static void __init __gic_init(unsigned long gic_base_addr,
> >   	__gic_base_addr = gic_base_addr;
> >   
> >   	gic_base = ioremap_nocache(gic_base_addr, gic_addrspace_size);
> > +	if (!gic_base)
> > +		panic("Failed to map GIC memory");
> So you're replacing a panic due to dereferencing a NULL pointer with
> another panic -- not much progress here. I appreciate that the message
> is a bit more explicit, but is there something slightly less drastic we
> could do? Like returning an error code and see if the kernel otherwise
> recovers (possibly with reduced functionality)?
>
> >   
> >   	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
> >   	gic_shared_intrs = (gicconfig & GIC_SH_CONFIG_NUMINTRS_MSK) >>
> Thanks,
>
> 	M.