Re: [PATCH] scsi: ibmvscsis: Fix a stringop-overflow warning

[Laura Abbott]

On 09/11/2018 07:34 AM, Bryant G. Ly wrote:
> On 9/10/18 6:30 PM, Kees Cook wrote:
>
> > On Mon, Sep 10, 2018 at 3:37 PM, Laura Abbott <labbott@xxxxxxxxxx> wrote:
> > > There's currently a warning about string overflow with strncat:
> > >
> > > drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c: In function 'ibmvscsis_probe':
> > > drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c:3479:2: error: 'strncat' specified
> > > bound 64 equals destination size [-Werror=stringop-overflow=]
> > >    strncat(vscsi->eye, vdev->name, MAX_EYE);
> > >    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >
> > > Switch to using strlcat which correctly accounts for lengths that
> > > are equal to the destination buffer.
> > >
> > > Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> > > ---
> > >   drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> > > index fac377320158..53d344d8dc43 100644
> > > --- a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> > > +++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
> > > @@ -3475,7 +3475,7 @@ static int ibmvscsis_probe(struct vio_dev *vdev,
> > >                  vscsi->dds.window[REMOTE].liobn);
> > >
> > >          strcpy(vscsi->eye, "VSCSI ");
> > > -       strncat(vscsi->eye, vdev->name, MAX_EYE);
> > > +       strlcat(vscsi->eye, vdev->name, MAX_EYE);
> > Can this just get switched to snprintf() instead?
> >
> > snprintf(vscsi->eye, sizeof(vscsi->eye), "VSCSI%s", vdev->name);
>
> Either works for me.

I'll switch to the snprintf since that's cleaner.

> > >          vscsi->dds.unit_id = vdev->unit_address;
> > >          strncpy(vscsi->dds.partition_name, partition_name,
> > And does this strncpy need a NUL-termination and/or trailing padding?
> Yes, good catch, it does need NUL-termination.

I can send that cleanup in a second patch.

> -Bryant