This is a note to let you know that I've just added the patch titled
KVM: Don't null dereference ops->destroy
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-don-t-null-dereference-ops-destroy.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c4c1a8afd529cb811439fe472a1dfd710f1916d4
Author: Alexey Kardashevskiy <aik@xxxxxxxxx>
Date: Wed Jun 1 03:43:28 2022 +0200
KVM: Don't null dereference ops->destroy
[ Upstream commit e8bc2427018826e02add7b0ed0fc625a60390ae5 ]
A KVM device cleanup happens in either of two callbacks:
1) destroy() which is called when the VM is being destroyed;
2) release() which is called when a device fd is closed.
Most KVM devices use 1) but Book3s's interrupt controller KVM devices
(XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during
the machine execution. The error handling in kvm_ioctl_create_device()
assumes destroy() is always defined which leads to NULL dereference as
discovered by Syzkaller.
This adds a checks for destroy!=NULL and adds a missing release().
This is not changing kvm_destroy_devices() as devices with defined
release() should have been removed from the KVM devices list by then.
Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 287444e52ccf..4b445dddb798 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3329,8 +3329,11 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
kvm_put_kvm(kvm);
mutex_lock(&kvm->lock);
list_del(&dev->vm_node);
+ if (ops->release)
+ ops->release(dev);
mutex_unlock(&kvm->lock);
- ops->destroy(dev);
+ if (ops->destroy)
+ ops->destroy(dev);
return ret;
}
