Re: [PATCH] 3c507.c: remove unused NULL pointer check

Stephen Hemminger
2009-12-21T20:31:24Z

On Mon, 21 Dec 2009 17:56:39 +0100
Oliver Hartkopp <socketcan@hartkopp.net> wrote:

> Alexander Strakh wrote:
> > In driver drivers/net/3c507.c in function Iirqreturn_t el16_interrupt:
> > 1. If in line 555 dev = NULL then we goto line 556
> > 2. In line 556 we have null dereference because pr_err called with dev->name
> > in third parameter.
> > 555 if (dev == NULL) {
> > 556 pr_err("%s: net_interrupt(): irq %d for unknown device.
> > \n",
> > 557 dev->name, irq);
> > 558 return IRQ_NONE;
> > 559 }
> >
> > Found by Linux Device Drivers Verification (Svace detector)
> >
> > Remove unused NULL pointer check.
>
> You are obviously doing more than that ...
>
> >
> > Signed-off-by: Alexander Strakh <strakh@ispras.ru>
> >
> > ---
> > diff --git a/./0000/drivers/net/3c507.c b/./moder/drivers/net/3c507.c
> > index fbc2311..3bfb3dd 100644
> > --- a/./0000/drivers/net/3c507.c
> > +++ b/./moder/drivers/net/3c507.c
> > @@ -552,12 +552,6 @@ static irqreturn_t el16_interrupt(int irq, void *dev_id)
> > ushort ack_cmd = 0;
> > void __iomem *shmem;
> >
> > - if (dev == NULL) {
> > - pr_err("%s: net_interrupt(): irq %d for unknown device.\n",
> > - dev->name, irq);
>
> You are changing real funcionality here!
>
> If you want to fix it, fix the pr_err() but do not remove the "return
> IRQ_NONE" entirely.
>
> This looks like an introduction of a bug.
>
> Regards,
> Oliver
>
>
> > - return IRQ_NONE;
> > - }
> > -

Interrupts will never be called with third parameter of NULL. It is really
bogus impossible to reach code.

--