Re: [PATCH] TPM: integrity fix

[Rajiv Andrade]

Serge E. Hallyn wrote:
> Quoting Rajiv Andrade (srajiv@xxxxxxxxxxxxxxxxxx):
>   
> > Fix to function which is called by IMA, now tpm_chip_find_get() considers the case in which the machine doesn't have a TPM or, if it has, its TPM isn't enabled.
> >
> > Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Rajiv Andrade <srajiv@xxxxxxxxxxxxxxxxxx>
> >     
>
> Is this to fix James' problem with IMA on bootup?
>
>   
Yes.
> Acked-by: Serge Hallyn <serue@xxxxxxxxxx>
>
>   
> > ---
> >  drivers/char/tpm/tpm.c |    8 +++++---
> >  1 files changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
> > index 0387965..912a473 100644
> > --- a/drivers/char/tpm/tpm.c
> > +++ b/drivers/char/tpm/tpm.c
> > @@ -666,18 +666,20 @@ EXPORT_SYMBOL_GPL(tpm_show_temp_deactivated);
> >   */
> >  static struct tpm_chip *tpm_chip_find_get(int chip_num)
> >  {
> > -	struct tpm_chip *pos;
> > +	struct tpm_chip *pos, *chip = NULL;
> >
> >  	rcu_read_lock();
> >  	list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
> >     
>
> Crap I even paused for a second when I reviewed the original
> patch.  I think the conversation in my head went something like
> "but will pos be NULL at the end of the loop?"  "Oh, it must".  gah.
>
>   
Yeah, I thought the same and let it pass by..

Rajiv
> >  		if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num)
> >  			continue;
> >
> > -		if (try_module_get(pos->dev->driver->owner))
> > +		if (try_module_get(pos->dev->driver->owner)) {
> > +			chip = pos;
> >  			break;
> > +		}
> >  	}
> >  	rcu_read_unlock();
> > -	return pos;
> > +	return chip;
> >  }
> >
> >  #define TPM_ORDINAL_PCRREAD cpu_to_be32(21)
> > --
> > 1.5.6.3
> >     

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