Re: [patch 2/2] staging: lustre: integer overflow in obd_ioctl_is_invalid()

[Dan Carpenter <dan.carpenter@oracle.com>]

On Fri, Apr 25, 2014 at 09:13:21AM +0200, walter harms wrote:
> 
> 
> Am 24.04.2014 23:49, schrieb Dan Carpenter:
> > The obd_ioctl_getdata() function caps "data->ioc_len" at
> > OBD_MAX_IOCTL_BUFFER and then calls this obd_ioctl_is_invalid() to check
> > that the other values inside data are valid.
> > 
> > There are several lengths inside data but when they are added together
> > they must not be larger than "data->ioc_len".  The checks against
> > "(data->ioc_inllen1 > (1<<30))" are supposed to ensure that the addition
> > does not have an integer overflow.  But "(1<<30) * 4" actually can
> > overflow 32 bits so the checks are insufficient.
> > 
> > I have changed it to "> OBD_MAX_IOCTL_BUFFER" instead.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > diff --git a/drivers/staging/lustre/lustre/include/lustre_lib.h b/drivers/staging/lustre/lustre/include/lustre_lib.h
> > index 0368ca6..04f549e 100644
> > --- a/drivers/staging/lustre/lustre/include/lustre_lib.h
> > +++ b/drivers/staging/lustre/lustre/include/lustre_lib.h
> > @@ -192,23 +192,23 @@ static inline int obd_ioctl_packlen(struct obd_ioctl_data *data)
> >  
> >  static inline int obd_ioctl_is_invalid(struct obd_ioctl_data *data)
> >  {
> > -	if (data->ioc_len > (1<<30)) {
> > +	if (data->ioc_len > OBD_MAX_IOCTL_BUFFER) {
> >  		CERROR("OBD ioctl: ioc_len larger than 1<<30\n");
> >  		return 1;
> >  	}
> 
> I would suggest to adjust the errormsg also like:
> CERROR("OBD ioctl: ioc_len larger than OBD_MAX_IOCTL_BUFFER\n");
> 
> otherwise future debuggers will be confused.
> 
> just my 2 cents
> 

Ah yes.  I will resend.

regards,
dan carpenter