Re: [PATCH] vTPM: Fix missing NULL check

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Mon, Jun 19, 2017 at 09:11:17AM +0800, Greg KH wrote:
> On Mon, Jun 19, 2017 at 01:43:21AM +0200, Jarkko Sakkinen wrote:
> > From: "Hon Ching \\(Vicky\\) Lo" <honclo@linux.vnet.ibm.com>
> > 
> > The current code passes the address of tpm_chip as the argument to
> > dev_get_drvdata() without prior NULL check in
> > tpm_ibmvtpm_get_desired_dma.  This resulted an oops during kernel
> > boot when vTPM is enabled in Power partition configured in active
> > memory sharing mode.
> > 
> > The vio_driver's get_desired_dma() is called before the probe(), which
> > for vtpm is tpm_ibmvtpm_probe, and it's this latter function that
> > initializes the driver and set data.  Attempting to get data before
> > the probe() caused the problem.
> > 
> > This patch adds a NULL check to the tpm_ibmvtpm_get_desired_dma.
> > 
> > fixes: 9e0d39d8a6a0 ("tpm: Remove useless priv field in struct tpm_vendor_specific")
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Hon Ching(Vicky) Lo <honclo@linux.vnet.ibm.com>
> > Reviewed-by: Jarkko Sakkine <jarkko.sakkinen@linux.intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> > Backport for v4.9. I asked to Vicky to test my backport so this should be OK.
> 
> Thanks for this, but next time can you give me a hint of what the git
> commit id is for the patch in Linus's tree?  I had to go dig it out by
> hand :(
> 
> greg k-h

I forgot it. I'm sorry. Has been in my previous backports and will be
in my future backports!

/Jarkko