Re: [PATCH] ata: libata-scsi: fix sloppy result type of ata_ioc32()

[Sergey Shtylyov <s.shtylyov@omp.ru>]

On 6/21/22 1:44 AM, Damien Le Moal wrote:
[...]
>>>> While ata_ioc32() returns *int*, its result gets assigned to and compared
>>>> with the *unsigned long* variable 'val' in ata_sas_scsi_ioctl(), its only
>>>> caller, which implies a problematic implicit cast -- fix that by returning
>>>> *unsigned long* instead.
>>>>
>>>> Found by Linux Verification Center (linuxtesting.org) with the SVACE static
>>>> analysis tool.
>>>>
>>>> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
>>>>
>>>> ---
>>>> This patch is against the 'for-next' branch of Damien's 'libata.git' repo.
>>>>
>>>>  drivers/ata/libata-scsi.c |    2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> Index: libata/drivers/ata/libata-scsi.c
>>>> ===================================================================
>>>> --- libata.orig/drivers/ata/libata-scsi.c
>>>> +++ libata/drivers/ata/libata-scsi.c
>>>> @@ -539,7 +539,7 @@ int ata_task_ioctl(struct scsi_device *s
>>>>  	return rc;
>>>>  }
>>>>  
>>>> -static int ata_ioc32(struct ata_port *ap)
>>>> +static unsigned long ata_ioc32(struct ata_port *ap)
>>>>  {
>>>>  	if (ap->flags & ATA_FLAG_PIO_DMA)
>>>>  		return 1;
>>
>>> Actually, this should be a bool I think and the ioctl code cleaned to use
>>
>>    By the ioctl code you mean ata_sas_scsi_ioctl()?
> 
> yes.
> 
>>> that type since the val argument of the ioctl is also used as a bool.
>>
>>    As for HDIO_SET_32BIT, that's prolly OK but what to do with HDIO_GET_32BIT
>> (it calls put_user() on *unsigned long*)?
> 
> Something like this should work fine:
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 86dbb1cdfabd..ec7f79cbb135 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
[...]
> @@ -571,16 +572,16 @@ int ata_sas_scsi_ioctl(struct ata_port *ap, struct
> scsi_device *scsidev,
>                 return put_user(val, (unsigned long __user *)arg);
> 
>         case HDIO_SET_32BIT:

   Hmm, I told you this *case* is prolly OK -- it was HDIO_GET_32BIT *case* that
I was concerned about... So you mean that HDIO_GET_32BIT handling should remain
intact?

> -               val = (unsigned long) arg;
> +               pio32 = !!((unsigned long) arg);
>                 rc = 0;
>                 spin_lock_irqsave(ap->lock, flags);
>                 if (ap->pflags & ATA_PFLAG_PIO32CHANGE) {
> -                       if (val)
> +                       if (pio32)
>                                 ap->pflags |= ATA_PFLAG_PIO32;
>                         else
>                                 ap->pflags &= ~ATA_PFLAG_PIO32;
>                 } else {
> -                       if (val != ata_ioc32(ap))
> +                       if (pio32 != ata_ioc32(ap))
>                                 rc = -EINVAL;
>                 }
>                 spin_unlock_irqrestore(ap->lock, flags);

   Not really sure this is worth it... *unsigned long* result type for
ata_ioc32() seems simpler.

MBR, Sergey