Re: [PATCH] tpm: Fix memory leak in tpmm_chip_alloc

[Guozihua (Scott)]

On 2022/3/7 21:45, Jarkko Sakkinen wrote:
> On Mon, Mar 07, 2022 at 06:48:27PM +0800, GUO Zihua wrote:
> > Fix a memory leak in tpmm_chip_alloc. devm_add_action_or_reset would
> > call put_device on error, while tpm->devs is left untouched. Call
> > put_device on tpm->devs as well if devm_add_action_or_reset returns an
> > error.
> >
> > Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm")
> > Signed-off-by: GUO Zihua <guozihua@xxxxxxxxxx>
> > ---
> >   drivers/char/tpm/tpm-chip.c | 13 +++++++++----
> >   1 file changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> > index b009e7479b70..0a92334e8c40 100644
> > --- a/drivers/char/tpm/tpm-chip.c
> > +++ b/drivers/char/tpm/tpm-chip.c
> > @@ -308,6 +308,12 @@ static int tpm_class_shutdown(struct device *dev)
> >   	return 0;
> >   }
> >   
> > +static void tpm_chip_free(struct tpm_chip *chip)
> > +{
> > +	put_device(&chip->devs);
> > +	put_device(&chip->dev);
> > +}
> > +
> >   /**
> >    * tpm_chip_alloc() - allocate a new struct tpm_chip instance
> >    * @pdev: device to which the chip is associated
> > @@ -396,8 +402,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
> >   	return chip;
> >   
> >   out:
> > -	put_device(&chip->devs);
> > -	put_device(&chip->dev);
> > +	tpm_chip_free(chip);
> >   	return ERR_PTR(rc);
> >   }
> >   EXPORT_SYMBOL_GPL(tpm_chip_alloc);
> > @@ -420,8 +425,8 @@ struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
> >   		return chip;
> >   
> >   	rc = devm_add_action_or_reset(pdev,
> > -				      (void (*)(void *)) put_device,
> > -				      &chip->dev);
> > +				      (void (*)(void *)) tpm_chip_free,
> > +				      chip);
> >   	if (rc)
> >   		return ERR_PTR(rc);
> >   
> > --
> > 2.17.1
>
> Please test against the latest in
>
> git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git
>
> and share your results.
>
> BR, Jarkko
> .

Hi Jarkko,

I'll do that. Do we have a test set for TPM? Or do we just build and run 
it and see if everything works as expected?

This is an error handling optimization BTW.

--
Best
GUO Zihua