Re: [PATCH] Fix pointer arithmetic in hpt3xx driver code (3rd try)

Re: [PATCH] Fix pointer arithmetic in hpt3xx driver code (3rd try)

[Sergei Shtylyov]

Hello.

Masoud Sharbiani wrote:

> git commit 74811f355f4f69a187fa74892dcf2a684b84ce99 causes crash at
> module load (or boot) time on my machine with a hpt374 controller.
> The reason for this is that for initializing second controller which sets
> (hwif->dev == host->dev[1]) to true (1), adds 1 to a void ptr, which
> advances it by one byte instead of advancing it by sizeof(hpt_info) bytes.
> Because of this, all initialization functions get corrupted data in info
> variable which causes a crash at boot time.
>
> This patch fixes that and makes my machine boot again.
>   

   This description is better, thanks. You could also mention that 
you're factoring out the code to get to the 'struct hpt_info' into a 
separate function...

> Signed-Off-By: Masoud Sharbiani <masouds@google.com>
>
> diff --git a/drivers/ide/pci/hpt366.c b/drivers/ide/pci/hpt366.c
> index eb107ee..4eae284 100644
> --- a/drivers/ide/pci/hpt366.c
> +++ b/drivers/ide/pci/hpt366.c
> @@ -613,6 +613,14 @@ static int check_in_drive_list(ide_drive_t *drive, const char **list)
>  	return 0;
>  }
>  
> +static struct hpt_info *hpt3xx_get_info(struct device *dev)
> +{
> +	struct ide_host *host	= pci_get_drvdata(to_pci_dev(pci_dev));
>   

   Oops, this just won't compile. :-/
   And please re-consider passing 'struct pci_dev *' to this function 
since it's pre-calculated by the callers and is used by them otherwise 
in 5 (not even 4) cases out of 7.

> +	struct hpt_info *info	= (struct hpt_info *)host->host_priv;
> +
> +	return dev == host->dev[1] ? info + 1 : info;
>   

    The 'dev' here would turn into '&dev->dev' if the parameter type 
would be changed.

MBR, Sergei

Re: [PATCH] Fix pointer arithmetic in hpt3xx driver code (3rd try)

[Sergei Shtylyov]

Hello, I wrote:
>> diff --git a/drivers/ide/pci/hpt366.c b/drivers/ide/pci/hpt366.c
>> index eb107ee..4eae284 100644
>> --- a/drivers/ide/pci/hpt366.c
>> +++ b/drivers/ide/pci/hpt366.c
>> @@ -613,6 +613,14 @@ static int check_in_drive_list(ide_drive_t 
>> *drive, const char **list)
>>      return 0;
>>  }
>>  
>> +static struct hpt_info *hpt3xx_get_info(struct device *dev)
>> +{
>> +    struct ide_host *host    = pci_get_drvdata(to_pci_dev(pci_dev));
>>   
>
>   Oops, this just won't compile. :-/

   BTW, there's no need to invoke to_pci_dev() at all since 
pci_get_drvdata(dev) boils down to dev_get_drvdata(&dev->dev) call. So, 
in order not to waste time on useless pointer tricks, we should just 
invoke the latter here.

>   And please re-consider passing 'struct pci_dev *' to this function 
> since it's pre-calculated by the callers and is used by them otherwise 
> in 5 (not even 4) cases out of 7.
>

   Well, since to_pci_dev() is unnecessary here, I'm taking my request 
back. :-)

MBR, Sergei

Re: [PATCH] Fix pointer arithmetic in hpt3xx driver code (3rd try)

[Bartlomiej Zolnierkiewicz]

Hi,

Masoud/Sergei: sorry for the bug and thanks for fixing it.

On Sunday 07 September 2008, Sergei Shtylyov wrote:
> Hello, I wrote:
> >> diff --git a/drivers/ide/pci/hpt366.c b/drivers/ide/pci/hpt366.c
> >> index eb107ee..4eae284 100644
> >> --- a/drivers/ide/pci/hpt366.c
> >> +++ b/drivers/ide/pci/hpt366.c
> >> @@ -613,6 +613,14 @@ static int check_in_drive_list(ide_drive_t 
> >> *drive, const char **list)
> >>      return 0;
> >>  }
> >>  
> >> +static struct hpt_info *hpt3xx_get_info(struct device *dev)
> >> +{
> >> +    struct ide_host *host    = pci_get_drvdata(to_pci_dev(pci_dev));
> >>   
> >
> >   Oops, this just won't compile. :-/
> 
>    BTW, there's no need to invoke to_pci_dev() at all since 
> pci_get_drvdata(dev) boils down to dev_get_drvdata(&dev->dev) call. So, 
> in order not to waste time on useless pointer tricks, we should just 
> invoke the latter here.

I corrected this and applied the patch.

Re: [PATCH] Fix pointer arithmetic in hpt3xx driver code (3rd try)

[Masoud Sharbiani]

On Sun, Sep 07, 2008 at 08:10:03PM +0200, Bartlomiej Zolnierkiewicz wrote:
> 
> Hi,
> 
> Masoud/Sergei: sorry for the bug and thanks for fixing it.
> 
> On Sunday 07 September 2008, Sergei Shtylyov wrote:
> > Hello, I wrote:
> > >> diff --git a/drivers/ide/pci/hpt366.c b/drivers/ide/pci/hpt366.c
> > >> index eb107ee..4eae284 100644
> > >> --- a/drivers/ide/pci/hpt366.c
> > >> +++ b/drivers/ide/pci/hpt366.c
> > >> @@ -613,6 +613,14 @@ static int check_in_drive_list(ide_drive_t 
> > >> *drive, const char **list)
> > >>      return 0;
> > >>  }
> > >>  
> > >> +static struct hpt_info *hpt3xx_get_info(struct device *dev)
> > >> +{
> > >> +    struct ide_host *host    = pci_get_drvdata(to_pci_dev(pci_dev));
> > >>   
> > >
> > >   Oops, this just won't compile. :-/
> > 
> >    BTW, there's no need to invoke to_pci_dev() at all since 
> > pci_get_drvdata(dev) boils down to dev_get_drvdata(&dev->dev) call. So, 
> > in order not to waste time on useless pointer tricks, we should just 
> > invoke the latter here.
> 
> I corrected this and applied the patch.

Thanks!

Masoud