lkml.org 
[lkml]   [2007]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] USB Pegasus driver - avoid a potential NULL pointer dereference.
On 29/07/07, Satyam Sharma <satyam.sharma@gmail.com> wrote:
> Hi,
>
> On 7/29/07, Jesper Juhl <jesper.juhl@gmail.com> wrote:
> > Hello,
> >
> > This patch makes sure we don't dereference a NULL pointer in
> > drivers/net/usb/pegasus.c::write_bulk_callback() in the initial
> > struct net_device *net = pegasus->net; assignment.
> > The existing code checks if 'pegasus' is NULL and bails out if
> > it is, so we better not touch that pointer until after that check.
> > [...]
> > diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
> > index a05fd97..04cba6b 100644
> > --- a/drivers/net/usb/pegasus.c
> > +++ b/drivers/net/usb/pegasus.c
> > @@ -768,11 +768,13 @@ done:
> > static void write_bulk_callback(struct urb *urb)
> > {
> > pegasus_t *pegasus = urb->context;
> > - struct net_device *net = pegasus->net;
> > + struct net_device *net;
> >
> > if (!pegasus)
> > return;
> >
> > + net = pegasus->net;
> > +
> > if (!netif_device_present(net) || !netif_running(net))
> > return;
>
> Is it really possible that we're called into this function with
> urb->context == NULL? If not, I'd suggest let's just get rid of
> the check itself, instead.
>
I'm not sure. I am not very familiar with this code. I just figured
that moving the assignment is potentially a little safer and it is
certainly no worse than the current code, so that's a safe and
potentially benneficial change. Removing the check may be safe but I'm
not certain enough to make that call...

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please http://www.expita.com/nomime.html
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-07-29 01:57    [W:0.158 / U:0.316 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site