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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2023-07-14 15:45:32 -0700
committerAlex Williamson <alex.williamson@redhat.com>2023-08-03 11:58:32 -0600
commit9e0f4f2918c2ff145d3dedee862d9919a6ed5812 (patch)
tree3507ddb40bdab5e88759b0e79a29496689eb976f /virt/kvm
parent094671300fea0e24fe1eb33b73b54863065490c9 (diff)
kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add()
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>
Diffstat (limited to 'virt/kvm')
-rw-r--r--virt/kvm/vfio.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 07cb5f44b2a2..59945f6001f4 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;