Linus Lüssing wrote:
> Hi everyone,
> 
> By accident I've typed in a mesh interface name for batman-adv which
> already existed as a real interface. This produces a null pointer
> dereference in orig_hash_add_if():
> http://www.open-mesh.org/ticket/146
> 
> The attached patch shall illustrate the problem, but I'm not quite
> satisfied with it. Although it seems to "fix" the problem and gets
> rid of the call trace, it is probably still very racy. Does anyone
> have an idea for a more sane but equally easy check to fix the issue?
> Or is the only sane solution to hold an rcu-lock and compare the
> hard_iface->soft_iface in hardif_enable_interface() with every
> hard-iface->net_dev from the hardif_list?
> 
> Cheers, Linus

Oh, it doesn't fix anything - it just works by accident. :)
You are just happy that bat_priv->orig_hash is still memory that is accessible 
by us and is zero.

Let me suggest another patch (may take a while).

Best regards,
	Sven