From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: "Winkler, Tomas" <tomas.winkler@intel.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>
Subject: Re: [PATCH] tpm: fix incorrect success returns from tpm_try_transmit()
Date: Thu, 3 Jan 2019 17:03:47 +0200 [thread overview]
Message-ID: <20190103150347.GB17015@linux.intel.com> (raw)
In-Reply-To: <5B8DA87D05A7694D9FA63FD143655C1B9DA62640@hasmsx108.ger.corp.intel.com>
On Thu, Jan 03, 2019 at 01:37:09PM +0000, Winkler, Tomas wrote:
> >
> > On Mon, Dec 31, 2018 at 10:27:31AM -0800, James Bottomley wrote:
> > > Ever since 627448e85c766 "tpm: separate cmd_ready/go_idle from
> > > runtime_pm" we have been returning success from tpm_try_transmit()
> > > even if an error occurred. The reason is that the introduction of rc
> > > = tpm_go_idle() at the end of processing overwrites the value of rc if
> > > it contains an error code (mostly with success). Fix this by writing
> > > the return to a new variable rc1 instead.
> > >
> > > Fixes: 627448e85c766 "tpm: separate cmd_ready/go_idle from runtime_pm"
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> > >
> > > ---
> > >
> > > Note: the goto out looks fishy as well. The only go_idle implementor
> > > is tpm_crb and that can return a timeout as -ETIME, so it looks like
> > > it would then loop forever
> > >
> > > diff --git a/drivers/char/tpm/tpm-interface.c
> > > b/drivers/char/tpm/tpm-interface.c
> > > index 129f640424b7..ac7ebab6140c 100644
> > > --- a/drivers/char/tpm/tpm-interface.c
> > > +++ b/drivers/char/tpm/tpm-interface.c
> > > @@ -432,7 +432,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip
> > *chip,
> > > unsigned int flags)
> > > {
> > > struct tpm_output_header *header = (void *)buf;
> > > - int rc;
> > > + int rc, rc1;
> > > ssize_t len = 0;
> > > u32 count, ordinal;
> > > unsigned long stop;
> > > @@ -547,8 +547,8 @@ static ssize_t tpm_try_transmit(struct tpm_chip
> > *chip,
> > > dev_err(&chip->dev, "tpm2_commit_space: error %d\n", rc);
> > >
> > > out:
> > > - rc = tpm_go_idle(chip, flags);
> > > - if (rc)
> > > + rc1 = tpm_go_idle(chip, flags);
> > > + if (rc1)
> > > goto out;
> > >
> > > if (need_locality)
> >
> > Thanks James and sorry for latency (holiday season). Just a small suggestion. I
> > would just:
> >
> > if (tpm_go_idle(chip, flags))
> > goto out;
> >
> > What do you think?
>
>
> This is wrong as well because of the jump to 'out'.
> I've introduced this bug in version 4 of the patch, when the wrappers were added, before the jump to 'out' was correct.
> If it's okay with you I will post my version of the fix.
> Thanks
> Tomas
Works for me.
/Jarkko
next prev parent reply other threads:[~2019-01-03 15:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-31 18:27 [PATCH] tpm: fix incorrect success returns from tpm_try_transmit() James Bottomley
2019-01-03 12:59 ` Jarkko Sakkinen
2019-01-03 13:37 ` Winkler, Tomas
2019-01-03 15:03 ` Jarkko Sakkinen [this message]
2019-01-03 15:23 ` James Bottomley
2019-01-03 15:34 ` Winkler, Tomas
2019-01-03 16:17 ` James Bottomley
2019-01-10 17:16 ` Jarkko Sakkinen
2019-01-10 17:16 ` Jarkko Sakkinen
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