From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: peterhuewe@gmx.de, jgg@ziepe.ca, linux-integrity@vger.kernel.org,
linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
jgross@suse.com, dunlapg@umich.edu,
"Dr. Greg Wettstein" <greg@wind.enjellic.com>,
"Dr . Greg Wettstein" <greg@enjellic.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2] tpm: Restore functionality to xen vtpm driver.
Date: Tue, 18 Sep 2018 00:19:00 +0300 [thread overview]
Message-ID: <20180917211900.GD6716@linux.intel.com> (raw)
In-Reply-To: <b82c4603-1a60-16ec-14b6-81251e114b75@oracle.com>
On Mon, Sep 17, 2018 at 09:54:37AM -0400, Boris Ostrovsky wrote:
> On 9/16/18 3:25 PM, Jarkko Sakkinen wrote:
> > On Thu, Sep 13, 2018 at 05:25:51PM -0400, Boris Ostrovsky wrote:
> >> From: "Dr. Greg Wettstein" <greg@wind.enjellic.com>
> >>
> >> Functionality of the xen-tpmfront driver was lost secondary to
> >> the introduction of xenbus multi-page support in commit ccc9d90a9a8b
> >> ("xenbus_client: Extend interface to support multi-page ring").
> >>
> >> In this commit a pointer to the shared page address was being
> >> passed to the xenbus_grant_ring() function rather then the
> >> address of the shared page itself. This resulted in a situation
> > I'm sorry but I'm far from being expert with Xen and this sentence
> > confuses me so maybe could open it up a bit.
> >
> > For me "shared page address" and "address of the shared page" are
> > the same thing. What am I missing? I mean just different forms in
> > english to describe the exact same thing...
>
> xenbus_grant_ring() takes as an argument address of the ring shared
> between two guests. What Greg was trying to describe was the fact that
> existing code instead passes address of location where this address is
> stored (i.e. somewhat similar to difference between pointer and pointer
> to a pointer).
Just to understand this bug better why did not the wrong version
cause any undefined behavior? Sounds like a fatal bug. Does this
cause crashes?
> Would this be better:
>
> "In this commit pointer to location of the where the shared page address
> is stored was being passed to the xenbus_grant_ring() function rather
> then the
> address of the shared page itself."
Yes, definitely!
> Or please suggest a better alternative, I'll be happy to amend the
> commit message.
Thank you.
> Thanks.
> -boris
/Jarkko
next prev parent reply other threads:[~2018-09-17 21:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-13 21:25 [PATCH v2] tpm: Restore functionality to xen vtpm driver Boris Ostrovsky
2018-09-16 19:25 ` Jarkko Sakkinen
2018-09-17 13:54 ` Boris Ostrovsky
2018-09-17 21:19 ` Jarkko Sakkinen [this message]
2018-09-17 22:25 ` Boris Ostrovsky
2018-09-18 6:54 ` [Xen-devel] " Dag Nygren
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