Array subscript above array bounds warning

Array subscript above array bounds warning

[Tony Prisk]

Could someone clarify for me what I am missing here?


in drivers/net/ethernet/via/velocity.h is the following definition:

struct mac_regs {
volatile u8 PAR[6]; /* 0x00 */
...
}

I am trying to add the following function but it keeps giving array 
bounds warnings:

static void velocity_set_power_state(struct velocity_info *vptr, char state)
{
struct mac_regs __iomem *regs = vptr->mac_regs;

if (vptr->bustype == BUS_PCI) {
pci_set_power_state(vptr->pdev, state);
} else {
writeb(state, (&regs->PAR[0]) + 0x154);
}
}

gives:

/home/sentient/linux-git/server/arch/arm/include/asm/io.h:83:2: warning: 
array subscript is above array bounds [-Warray-bounds]


If I change the function to:

static void velocity_set_power_state(struct velocity_info *vptr, char state)
{
void __iomem *addr;
struct mac_regs __iomem *regs = vptr->mac_regs;

if (vptr->bustype == BUS_PCI)
pci_set_power_state(vptr->pdev, state);
else {
addr = &regs->PAR[0];
writeb(state, addr + 0x154);
}
}

I get the following warning:

drivers/net/ethernet/via/via-velocity.c:99:8: warning: assignment 
discards ?volatile? qualifier from pointer target type [enabled by default]


What is the correct way to go about this?

Regards
Tony Prisk

Array subscript above array bounds warning

[Emilio López]

El 27/04/13 20:29, Tony Prisk escribi?:
> Could someone clarify for me what I am missing here?
> 
> 
> in drivers/net/ethernet/via/velocity.h is the following definition:
> 
> struct mac_regs {
> volatile u8 PAR[6]; /* 0x00 */
> ...
> }
> 
> I am trying to add the following function but it keeps giving array
> bounds warnings:
> 
> static void velocity_set_power_state(struct velocity_info *vptr, char
> state)
> {
> struct mac_regs __iomem *regs = vptr->mac_regs;
> 
> if (vptr->bustype == BUS_PCI) {
> pci_set_power_state(vptr->pdev, state);
> } else {
> writeb(state, (&regs->PAR[0]) + 0x154);

This would be equivalent to

writeb(state, regs->PAR + 0x154);

or

writeb(state, &regs->PAR[340]);

Which would be out of bounds, right? As it's an u8 array with just 6
elements, not 341+

Array subscript above array bounds warning

[Tony Prisk]

On 28/04/13 11:54, Emilio L?pez wrote:
> El 27/04/13 20:29, Tony Prisk escribi?:
>> Could someone clarify for me what I am missing here?
>>
>>
>> in drivers/net/ethernet/via/velocity.h is the following definition:
>>
>> struct mac_regs {
>> volatile u8 PAR[6]; /* 0x00 */
>> ...
>> }
>>
>> I am trying to add the following function but it keeps giving array
>> bounds warnings:
>>
>> static void velocity_set_power_state(struct velocity_info *vptr, char
>> state)
>> {
>> struct mac_regs __iomem *regs = vptr->mac_regs;
>>
>> if (vptr->bustype == BUS_PCI) {
>> pci_set_power_state(vptr->pdev, state);
>> } else {
>> writeb(state, (&regs->PAR[0]) + 0x154);
> This would be equivalent to
>
> writeb(state, regs->PAR + 0x154);
>
> or
>
> writeb(state, &regs->PAR[340]);
>
> Which would be out of bounds, right? As it's an u8 array with just 6
> elements, not 341+
Yeah sorry - stupid question.

I just thought about the code while out for a walk and realised I should 
have looked at what the original author was trying to do rather than 
copy it verbatim.I have solved the issue now.

Regards
Tony P