linux-kernel - Re: [PATCH] tpm: Fix memory leak in tpmm_chip

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Date:   Fri, 11 Mar 2022 18:34:10 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     "Guozihua (Scott)" <guozihua@...wei.com>
Cc:     linux-integrity@...r.kernel.org, wangweiyang2@...wei.com,
        xiujianfeng@...wei.com, weiyongjun1@...wei.com, peterhuewe@....de,
        jgg@...pe.ca, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: Fix memory leak in tpmm_chip_alloc

On Thu, 2022-03-10 at 11:33 +0800, Guozihua (Scott) wrote:
> 
> 
> 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@...wei.com>
> > > ---
> > >   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.

There is kselftest in tools/testing/kselftes/tpm2 that you can use
but do not have to.

BR, Jarkko