From: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: jgg@ziepe.ca, dledford@redhat.com, Jann Horn <jannh@google.com>,
linux-rdma@vger.kernel.org,
Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>,
linux-mm@kvack.org, Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH for-rc v2] IB/hfi1: Move cached value of mm into handler
Date: Thu, 12 Nov 2020 17:08:22 -0500 [thread overview]
Message-ID: <ba7df075-ab50-3344-aacb-656ae10b517a@cornelisnetworks.com> (raw)
In-Reply-To: <b45c2303-a78e-a3b6-fcd2-371886caf788@cornelisnetworks.com>
On 11/12/2020 5:06 PM, Dennis Dalessandro wrote:
> On 11/12/2020 12:14 PM, Ira Weiny wrote:
>> On Wed, Nov 11, 2020 at 09:58:37PM -0500, Dennis Dalessandro wrote:
>>> Two earlier bug fixes have created a security problem in the hfi1
>>> driver. One fix aimed to solve an issue where current->mm was not valid
>>> when closing the hfi1 cdev. It attempted to do this by saving a cached
>>> value of the current->mm pointer at file open time. This is a problem if
>>> another process with access to the FD calls in via write() or ioctl() to
>>> pin pages via the hfi driver. The other fix tried to solve a use after
>>> free by taking a reference on the mm. This was just wrong because its
>>> possible for a race condition between one process with an mm that opened
>>> the cdev if it was accessing via an IOCTL, and another process
>>> attempting to close the cdev with a different current->mm.
>>
>> Again I'm still not seeing the race here. It is entirely possible
>> that the fix
>> I was trying to do way back was mistaken too... ;-) I would just
>> delete the
>> last 2 sentences... and/or reference the commit of those fixes and help
>> explain this more.
>
> I was attempting to refer to [1], the email that started all of this.
That link should be:
[1] https://marc.info/?l=linux-rdma&m=159891753806720&w=2
-Denny
next prev parent reply other threads:[~2020-11-12 22:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 2:58 Dennis Dalessandro
2020-11-12 17:14 ` Ira Weiny
2020-11-12 22:06 ` Dennis Dalessandro
2020-11-12 22:08 ` Dennis Dalessandro [this message]
2020-11-13 0:02 ` Jason Gunthorpe
2020-11-13 0:33 ` Ira Weiny
2020-11-13 13:37 ` Dennis Dalessandro
2020-11-13 18:31 ` Ira Weiny
2020-11-13 0:01 ` Jason Gunthorpe
2020-11-13 0:42 ` Ira Weiny
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