linux-kernel - Re: [tpmdd-devel] [PATCH RFC v3 5/5] tpm2: expose resource manager via a device link /dev/tpms<n>

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Message-ID: <1484587697.2540.39.camel@HansenPartnership.com>
Date:   Mon, 16 Jan 2017 09:28:17 -0800
From:   James Bottomley <James.Bottomley@...senPartnership.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:     open list <linux-kernel@...r.kernel.org>,
        linux-security-module@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net
Subject: Re: [tpmdd-devel] [PATCH RFC v3 5/5] tpm2: expose resource manager
 via a device link /dev/tpms<n>

On Mon, 2017-01-16 at 19:24 +0200, Jarkko Sakkinen wrote:
> On Mon, Jan 16, 2017 at 09:14:13AM -0700, Jason Gunthorpe wrote:
> > On Mon, Jan 16, 2017 at 03:12:11PM +0200, Jarkko Sakkinen wrote:
> > 
> > > @@ -199,7 +227,9 @@ struct tpm_chip *tpm_chip_alloc(struct device
> > > *pdev,
> > >  	return chip;
> > >  
> > >  out:
> > > +	put_device(&chip->devrm);
> > >  	put_device(&chip->dev);
> > > +	put_device(&chip->devrm);
> > >  	return ERR_PTR(rc);
> > >  }
> > 
> > Something has gone wrong here..
> 
> Not a big surprise. There were a bunch of these small patches
> that I had to squash. Thanks for spotting this.
> 
> Funny that I didn't experiece any issues when I run my smoke
> tests.

It's the error path in tpm_chip_alloc: it's incredibly hard to trigger,
which is probably why your tests didn't see it.  You basically either
have to be out of kernel memory or out of TPM device numbers.

James