linux-kernel - Re: [PATCH] tpm: Revert "tpm: fix invalid locking in NONBLOCKING mode"

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Message-ID: <1590538702.3576.2.camel@HansenPartnership.com>
Date:   Tue, 26 May 2020 17:18:22 -0700
From:   James Bottomley <James.Bottomley@...senPartnership.com>
To:     Alex Guzman <alex@...man.io>
Cc:     Mario Limonciello <Mario.Limonciello@...l.com>,
        Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jeffrin Jose T <jeffrin@...agiritech.edu.in>
Subject: Re: [PATCH] tpm: Revert "tpm: fix invalid locking in NONBLOCKING
 mode"

On Tue, 2020-05-26 at 16:31 -0700, Alex Guzman wrote:
> On Tue, May 26, 2020 at 4:06 PM James Bottomley
> <James.Bottomley@...senpartnership.com> wrote:
> > 
> > On Tue, 2020-05-26 at 15:19 -0700, Alex Guzman wrote:
> > [...]
> > > When using your patch, I get a hang when trying to use
> > > tpm2_getcap, and dmesg shows some info.
> > 
> > Are you sure it's all applied?  This
> > 
> > > [  570.913803]  tpm_tcg_write_bytes+0x2f/0x40
> > > [  570.913805]  release_locality+0x49/0x220
> > > [  570.913807]  tpm_relinquish_locality+0x1f/0x40
> > > [  570.913808]  tpm_chip_stop+0x21/0x40
> > > [  570.913810]  tpm_put_ops+0x9/0x30
> > > [  570.913811]  tpm_common_write+0x179/0x190
> > > [  570.913813]  vfs_write+0xb1/0x1a0
> > 
> > Implies an unmatched tpm_put_ops() in the async write path, as
> > though this hunk:
> > 
> > > @@ -211,11 +202,19 @@ ssize_t tpm_common_write(struct file *file,
> > > const char __user *buf,
> > >         if (file->f_flags & O_NONBLOCK) {
> > >                 priv->command_enqueued = true;
> > >                 queue_work(tpm_dev_wq, &priv->async_work);
> > > -               tpm_put_ops(priv->chip);
> > >                 mutex_unlock(&priv->buffer_mutex);
> > >                 return size;
> > >         }
> > 
> > Is missing.  I actually booted the patch in my TPM based VM and it
> > all seems to work OK when I execute tpm2_getcap (I verified it's
> > using O_NONBLOCK) and tssgetcapability in sync mode.
> > 
> > James
> > 
> 
> Oh, I did miss that bit. The patch had issues applying for some
> reason and I missed the single-line removal when I was looking at the
> diff.

Sorry, that's likely my fault: I did it on top of my current TPM tree.
I'll prepare a version against the vanilla kernel with a real
changelog.

> I gave it a spin on my machine again. getcap seems to work correctly
> with and without having the async config flag set for tpm2-tss. The
> pkcs11 plugin seems to work correctly again too. :)

Great, thanks!  I'll add your tested-by to the above.

James