linux-kernel - Re: [PATCH v2] s390/vfio-ap: fix memory leak in mdev remove callback

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Message-ID: <759f8840-671a-446c-875b-798dceb10d0f@linux.ibm.com>
Date:   Thu, 13 May 2021 10:18:44 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        borntraeger@...ibm.com, cohuck@...hat.com,
        pasic@...ux.vnet.ibm.com, jjherne@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        stable@...r.kernel.org, Tony Krowiak <akrowiak@...y.rr.com>
Subject: Re: [PATCH v2] s390/vfio-ap: fix memory leak in mdev remove callback



On 5/12/21 8:41 AM, Jason Gunthorpe wrote:
> On Mon, May 10, 2021 at 05:48:37PM -0400, Tony Krowiak wrote:
>> The mdev remove callback for the vfio_ap device driver bails out with
>> -EBUSY if the mdev is in use by a KVM guest. The intended purpose was
>> to prevent the mdev from being removed while in use; however, returning a
>> non-zero rc does not prevent removal. This could result in a memory leak
>> of the resources allocated when the mdev was created. In addition, the
>> KVM guest will still have access to the AP devices assigned to the mdev
>> even though the mdev no longer exists.
>>
>> To prevent this scenario, cleanup will be done - including unplugging the
>> AP adapters, domains and control domains - regardless of whether the mdev
>> is in use by a KVM guest or not.
>>
>> Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback")
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Tony Krowiak <akrowiak@...y.rr.com>
>> ---
>>   drivers/s390/crypto/vfio_ap_ops.c | 13 ++-----------
>>   1 file changed, 2 insertions(+), 11 deletions(-)
> Can you please ensure this goes to a -rc branch or through Alex's
> tree?

I'm sorry, I don't know what a -rc branch is nor how to push this
to Alex's tree, but I'd be happy to do so if you tell me now:)

>
> Thanks,
> Jason