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Commit 17046571 authored by Alexey Kardashevskiy's avatar Alexey Kardashevskiy Committed by Greg Kroah-Hartman
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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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 6098562e

virt/kvm/kvm_main.c

+4 −1
Original line number Diff line number Diff line
@@ -3329,7 +3329,10 @@ 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);

		if (ops->destroy)

			ops->destroy(dev);

		return ret;

	}