linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418: array index used before limits check ?

linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418: array index used before limits check ?

[David Binderman]

Hello there,

[linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418]: (style) Array ind
ex 'k' is used before limits check.

   if (!io[k] && k < INTC_IRQPIN_REG_NR_MANDATORY) {

Suggest sanity check array index before use.

Regards

David Binderman

 		 	   		  

Re: linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418: array index used before limits check ?

[Thomas Gleixner]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 350 bytes --]

On Mon, 8 Jun 2015, David Binderman wrote:

> Hello there,
> 
> [linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418]: (style) Array ind
> ex 'k' is used before limits check.
> 
>    if (!io[k] && k < INTC_IRQPIN_REG_NR_MANDATORY) {
> 
> Suggest sanity check array index before use.

Which version of gcc is being stupid here?

Thanks,

	tglx

RE: linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418: array index used before limits check ?

[David Binderman]

Hello there Thomas,

----------------------------------------
>> [linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418]: (style) Array ind
>> ex 'k' is used before limits check.
>>
>>    if (!io[k] && k < INTC_IRQPIN_REG_NR_MANDATORY) {
>>
>> Suggest sanity check array index before use.
>
> Which version of gcc is being stupid here?

None of them. 

The original "(style)" message is from a static analysis tool called cppcheck.

I can't think of a situation where, if an array index needs checking, then
it should be checked *after* use.


Regards

David Binderman


 		 	   		  

RE: linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418: array index used before limits check ?

[Thomas Gleixner]

On Mon, 8 Jun 2015, David Binderman wrote:
> ----------------------------------------
> >> [linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418]: (style) Array ind
> >> ex 'k' is used before limits check.
> >>
> >>    if (!io[k] && k < INTC_IRQPIN_REG_NR_MANDATORY) {
> >>
> >> Suggest sanity check array index before use.
> >
> > Which version of gcc is being stupid here?
> 
> None of them. 
> 
> The original "(style)" message is from a static analysis tool called cppcheck.
> 
> I can't think of a situation where, if an array index needs checking, then
> it should be checked *after* use.

It does not check the array index. Read the complete code:

        for (k = 0; k < INTC_IRQPIN_REG_NR; k++) {
                io[k] = platform_get_resource(pdev, IORESOURCE_MEM, k);
                if (!io[k] && k < INTC_IRQPIN_REG_NR_MANDATORY) {

The array bound is INTC_IRQPIN_REG_NR and the check about which that
tool complains has nothing to do with array bounds. Completely valid
code.

Thanks,

	tglx

RE: linux-4.1-rc7/drivers/irqchip/irq-renesas-intc-irqpin.c:418: array index used before limits check ?

[David Binderman]

Hello there Thomas,

----------------------------------------
>> I can't think of a situation where, if an array index needs checking, then
>> it should be checked *after* use.
>
> It does not check the array index. Read the complete code:
>
> for (k = 0; k < INTC_IRQPIN_REG_NR; k++) {
> io[k] = platform_get_resource(pdev, IORESOURCE_MEM, k);
> if (!io[k] && k < INTC_IRQPIN_REG_NR_MANDATORY) {
>
> The array bound is INTC_IRQPIN_REG_NR and the check about which that
> tool complains has nothing to do with array bounds. Completely valid
> code.

After a deeper look at the code, agreed. False positive by the tool.

I also checked the rest of the /irqchip/ directory for other messages by
the tool and couldn't see anything else suspicious.

Regards

David Binderman