diff options
author | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2023-07-14 15:45:32 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-09-13 09:42:46 +0200 |
commit | a4ff4b54f38825a9cdbdd1d70d2341af99ff67e6 (patch) | |
tree | 89dcb8b7ec3926e6bc299e834d491853ab0fbcca /virt | |
parent | fef33ca5e28c876ddeddd586d090fd872a06fca7 (diff) |
kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add()
[ Upstream commit 9e0f4f2918c2ff145d3dedee862d9919a6ed5812 ]
kvm_vfio_group_add() creates kvg instance, links it to kv->group_list,
and calls kvm_vfio_file_set_kvm() with kvg->file as an argument after
dropping kv->lock. If we race group addition and deletion calls, kvg
instance may get freed by the time we get around to calling
kvm_vfio_file_set_kvm().
Previous iterations of the code did not reference kvg->file outside of
the critical section, but used a temporary variable. Still, they had
similar problem of the file reference being owned by kvg structure and
potential for kvm_vfio_group_del() dropping it before
kvm_vfio_group_add() had a chance to complete.
Fix this by moving call to kvm_vfio_file_set_kvm() under the protection
of kv->lock. We already call it while holding the same lock when vfio
group is being deleted, so it should be safe here as well.
Fixes: 2fc1bec15883 ("kvm: set/clear kvm to/from vfio_group when group add/delete")
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230714224538.404793-1-dmitry.torokhov@gmail.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'virt')
-rw-r--r-- | virt/kvm/vfio.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c index af3d0cf06e4c..365d30779768 100644 --- a/virt/kvm/vfio.c +++ b/virt/kvm/vfio.c @@ -180,10 +180,10 @@ static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd) list_add_tail(&kvf->node, &kv->file_list); kvm_arch_start_assignment(dev->kvm); + kvm_vfio_file_set_kvm(kvf->file, dev->kvm); mutex_unlock(&kv->lock); - kvm_vfio_file_set_kvm(kvf->file, dev->kvm); kvm_vfio_update_coherency(dev); return 0; |