From: Jason Gunthorpe <jgg@nvidia.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
borntraeger@de.ibm.com, cohuck@redhat.com,
pasic@linux.vnet.ibm.com, jjherne@linux.ibm.com,
alex.williamson@redhat.com, kwankhede@nvidia.com
Subject: Re: [PATCH v3 2/2] s390/vfio-ap: control access to PQAP(AQIC) interception handler
Date: Wed, 19 May 2021 13:16:10 -0300 [thread overview]
Message-ID: <20210519161610.GO1002214@nvidia.com> (raw)
In-Reply-To: <20210519153921.804887-3-akrowiak@linux.ibm.com>
On Wed, May 19, 2021 at 11:39:21AM -0400, Tony Krowiak wrote:
> @@ -287,13 +289,17 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
> if (!(vcpu->arch.sie_block->eca & ECA_AIV))
> return -EOPNOTSUPP;
>
> - apqn = vcpu->run->s.regs.gprs[0] & 0xffff;
> - mutex_lock(&matrix_dev->lock);
> + rcu_read_lock();
> + pqap_module_hook = rcu_dereference(vcpu->kvm->arch.crypto.pqap_hook);
> + if (!pqap_module_hook) {
> + rcu_read_unlock();
> + goto set_status;
> + }
>
> - if (!vcpu->kvm->arch.crypto.pqap_hook)
> - goto out_unlock;
> - matrix_mdev = container_of(vcpu->kvm->arch.crypto.pqap_hook,
> - struct ap_matrix_mdev, pqap_hook);
> + matrix_mdev = pqap_module_hook->data;
> + rcu_read_unlock();
> + mutex_lock(&matrix_dev->lock);
The matrix_mdev pointer was extracted from the pqap_module_hook,
but now there is nothing protecting it since the rcu was dropped and
it gets freed in vfio_ap_mdev_remove.
And, again, module locking doesn't prevent vfio_ap_mdev_remove() from
being called. None of these patches should be combining module locking
with RCU.
Jason
next prev parent reply other threads:[~2021-05-19 16:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 15:39 [PATCH v3 0/2] s390/vfio-ap: fix memory leak in mdev remove callback Tony Krowiak
2021-05-19 15:39 ` [PATCH v3 1/2] " Tony Krowiak
2021-05-19 15:39 ` [PATCH v3 2/2] s390/vfio-ap: control access to PQAP(AQIC) interception handler Tony Krowiak
2021-05-19 16:16 ` Jason Gunthorpe [this message]
2021-05-19 23:04 ` Tony Krowiak
2021-05-19 23:22 ` Jason Gunthorpe
2021-05-20 1:08 ` Tony Krowiak
2021-05-20 8:48 ` Halil Pasic
2021-05-20 12:26 ` Jason Gunthorpe
2021-05-20 8:38 ` Halil Pasic
2021-05-20 12:51 ` Jason Gunthorpe
2021-05-21 18:24 ` Tony Krowiak
2021-05-21 18:30 ` Jason Gunthorpe
2021-05-19 17:21 ` Halil Pasic
2021-05-19 23:14 ` Tony Krowiak
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