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

Oliver Hartkopp
2009-12-21T20:46:25Z

Stephen Hemminger wrote:
> 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.

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

You're right! I just did not verify the direct assignment of dev = dev_id ...

Btw. the description for the reason of this patch remains unsuitably as the
problem is not the potential dereferencing of dev->name in pr_err() here.

It should better be something like this (partly stolen from your answer):

Interrupts will never be called with dev_id parameter of NULL.
This patch removes the obsolete, unreachable code.

Regards,
Oliver