From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: [PATCH 0/2] Protect against iommu driver disconnect Date: Thu, 25 Apr 2013 16:24:08 -0600 Message-ID: <20130425221546.14023.37372.stgit@bling.home> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mst@redhat.com To: alex.williamson@redhat.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Michael Tsirkin pointed out that file operations on /dev/vfio/vfio dereference iommu_driver and iommu_data without a lock. If releasing a group or unsetting the container occurs concurrently, we could race. We currently use a mutex when setting this association, so we can convert to a rwsem keeping the existing mutex critical sections as down_writes and add down_reads where these are used. Thanks, Alex --- Alex Williamson (2): vfio: Convert container->group_lock to rwsem vfio: Use down_reads to protect iommu disconnects drivers/vfio/vfio.c | 83 +++++++++++++++++++++++++++++++++++---------------- 1 file changed, 57 insertions(+), 26 deletions(-)