Re: [PATCH] 2.4.18 Eicon ISDN driver fix.

[petter wahlman <petter@bluezone.no>]

On Tue, 2002-02-26 at 20:54, Dave Jones wrote:
> On Tue, Feb 26, 2002 at 08:26:18PM +0100, petter wahlman wrote:
>  > +++ linux-2.4.18-pw/drivers/isdn/eicon/eicon_mod.c      Mon Feb 25
> 
>  > -                       if (user)
>  > +                       if (user) {
>  > +                               spin_unlock_irqrestore(&eicon_lock,
>  > flags);
>  >                                 copy_to_user(p, skb->data, cnt);
>  > +                               spin_lock_irqsave(&eicon_lock, flags);
>  > +                       }
> 
> What happens if something else adds/removes to card->statq, or
> frees the skb after you drop the lock?  I'm not familiar with
> this code, but from a quick look, it looks like this introduces
> a race no ?
> 

Yes, it will introduce a new race.
I did not actually intend to send this unfinished patch, but fscked up
:)
Anyway, calling copy_to_user while holding a spinlock is defiantly a bad
idea.


> -- 
> | Dave Jones.        http://www.codemonkey.org.uk
> | SuSE Labs
> 

Petter Wahlman.