On Fri, Jul 25, 2014 at 02:25:06PM +0200, Guillaume CLÉMENT wrote:
> On Fri, Jul 25, 2014 at 02:52:34PM +0300, Dan Carpenter wrote:
> > On Fri, Jul 25, 2014 at 01:07:40AM +0200, Guillaume Clement wrote:
> > > diff --git a/drivers/staging/vt6655/iwctl.c b/drivers/staging/vt6655/iwctl.c
> > > index 501cd64..9291259 100644
> > > --- a/drivers/staging/vt6655/iwctl.c
> > > +++ b/drivers/staging/vt6655/iwctl.c
> > > @@ -1621,14 +1621,17 @@ int iwctl_giwauth(struct net_device *dev,
> > > int iwctl_siwgenie(struct net_device *dev,
> > > struct iw_request_info *info,
> > > struct iw_point *wrq,
> > > - char *extra)
> > > + char __user *extra)
> > > {
> > > PSDevice pDevice = (PSDevice)netdev_priv(dev);
> > > PSMgmtObject pMgmt = &(pDevice->sMgmtObj);
> > > int ret = 0;
> > > + char length;
> > >
> > > if (wrq->length) {
> > > - if ((wrq->length < 2) || (extra[1]+2 != wrq->length)) {
> > > + if (get_user(length, extra + 1))
> > > + return -EFAULT;
> > > + if ((wrq->length < 2) || (length != wrq->length)) {
> > > ret = -EINVAL;
> > > goto out;
> > > }
> >
> > Wow, this is confusing code. The patch description isn't clear enough
> > that this is a bugfix patch and not just a "tag data" patch.
> >
> > I don't think this is correct. We need to check the length of the input
> > buffer before we call get_user(). Can we return directly or do we
> > *need* to go to the mysteriously named "out"? Also the + 2 is lost,
> > this would break everything if the current code works (not necessarily a
> > valid assumption). Delete all my comments in the final code.
>
> In this case, the "out" label just does "return ret;". But I agree this
> is better practice to jump to out, in case this changes at a later time,
> and to keep the code consistent.
>
No, absolutely not. "out" labels are the worst. We shouldn't make the
code unreadable and mysterious *now* just because of something which
is possible but frankly unlikely "at some later time".
Feel free to return directly if you want.
regards,
dan carpenter
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