On Tue, 4 Sep 2007, Satyam Sharma wrote:
> Hi Micah,
>
>
> On Tue, 4 Sep 2007, Micah Gruber wrote:
>
> > This patch fixes a potential null dereference bug where we dereference
> > dev before a null check. This patch simply moves the dereferencing after
> > the null check.
> >
> > Signed-off-by: Micah Gruber <[EMAIL PROTECTED]>
> > ---
> >
> > --- a/drivers/net/tulip/uli526x.c
> > +++ b/drivers/net/tulip/uli526x.c
> > @@ -663,7 +663,7 @@
> > {
> > struct net_device *dev = dev_id;
> > struct uli526x_board_info *db = netdev_priv(dev);
> > - unsigned long ioaddr;
> > + unsigned long ioaddr = dev->base_addr;
> > unsigned long flags;
> >
> > if (!dev) {
> > @@ -671,8 +671,6 @@
> > return IRQ_NONE;
> > }
> >
> > - ioaddr = dev->base_addr;
> > -
> > spin_lock_irqsave(&db->lock, flags);
> > outl(0, ioaddr + DCR7);
>
>
> [The patch is reversed.]
>
> But it is also complete -- you've left out the "netdev_priv(dev)"
^^^^^^^^
I meant: incomplete
> statement _just_ before the dereference that you've pushed down.
> Coverity wasn't smart enough to tell, but that's actually a dev->priv,
> so we'll _still_ be dereferencing dev before checking it for NULL below.
> And lastly, the patch isn't quite correct. It is the (!dev) check that
> is redundant and must be removed instead :-)
>
> I bet more such pointless checks exist all over. It makes more sense to
> remove them than unnecessarily try to solve "potential" NULL dereferences,
> that we (naturally) never saw earlier, because they're impossible. ISTR
> pointing out two similar patches a month or so back when Jeff pushed net
> driver patches upstream, IIRC ... ]
>
>
> Satyam
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