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SubjectRe: rionet: NULL pointer dereference
On Thu, 16 Jun 2011, Connor Hansen wrote:

> On Thu, Jun 16, 2011 at 3:06 PM, Jesper Juhl <jj@chaosbits.net> wrote:
> > Hi
> >
> > Just noticed that drivers/net/rionet.c::rionet_remove() can cause a NULL
> > deref when it calls unregister_netdev().
> > It initializes local variable 'ndev' to NULL and nothing changes this
> > before the call to unregister_netdev(ndev) - that functions then calls:
> > unregister_netdevice > unregister_netdevice_queue > list_move_tail >
> > __list_del_entry  which dereferences the pointer (which, being NULL, will
> > end in tears).
>
> unregister_netdevice(struct net_device *dev)
> {
> unregister_netdevice_queue(dev, NULL);
> }
>
> so unregister_netdevice_queue is being called with NULL,NULL
>
> void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
> {
> ASSERT_RTNL();
>
> if (head) {
> list_move_tail(&dev->unreg_list, head);
> } else {
> rollback_registered(dev);
> /* Finish processing unregister after unlock */
> net_set_todo(dev);
> }
> }
>
> if head is null, which it is from the call, then we call
> rollback_registered, and not list_move_tail()
>
> the else calls rollback_registered(NULL) then net_set_todo(NULL)
>
> both of which dereference null when passed, so yes there is a null
> dereference, just not in the code branch you thought.
>

Ahh crap, you are right. Too much coffee and too late to be reading kernel
code is my only excuse ;-)
Thanks for taking the time to look and correct me.


In any case, there's still a problem that needs to be fixed.

--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.
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