Re: [ 044/184] ALSA: ice1712: Initialize card->private_data

[Takashi Iwai]

At Fri, 7 Jun 2013 07:34:01 +0200,
Willy Tarreau wrote:
> 
> Hi Ben,
> 
> On Fri, Jun 07, 2013 at 04:48:58AM +0100, Ben Hutchings wrote:
> > > From: Sean Connor <sconnor004@xxxxxxxxxxxxx>
> > > 
> > > commit 69a4cfdd444d1fe5c24d29b3a063964ac165d2cd upstream.
> > > 
> > > Set card->private_data in snd_ice1712_create for fixing NULL
> > > dereference in snd_ice1712_remove().
> > 
> > This bug appears to have been introduced in Linux 3.8 and doesn't need
> > fixing in 2.6.32.
> 
> Ah indeed that's true. Does it harm to have it or not ?

It's harmless.

> because I'm
> still seeing a number of places where we have this in the driver :
> 
>    struct snd_ice1712 *ice = ac97->private_data;

These are different object types.  The reference of card->private_data
was introduced recently as Ben pointed out.

> I'd like to be sure that no other function risks to dereference the
> same pointer. Also, I'm noting that 3.0/3.4 have this fix, while 3.2
> does not. So I'm hesitant what to do with this patch.

Just overlooked in 3.0/3.4 reviews :-<

But it's utterly harmless, we don't have to remove it from 3.0/3.4, I
think.  

For 2.6.32, better to get rid of it from the queue, if it's not too
late.


thanks,

Takashi
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