On 07/02/2023 12:25, Jean-Philippe Brucker wrote:

On Fri, Jan 27, 2023 at 11:29:10AM +0000, Steven Price wrote:

quoted

+static int kvm_rme_config_realm(struct kvm *kvm, struct kvm_enable_cap *cap)
+{
+	struct kvm_cap_arm_rme_config_item cfg;
+	struct realm *realm = &kvm->arch.realm;
+	int r = 0;
+
+	if (kvm_realm_state(kvm) != REALM_STATE_NONE)
+		return -EBUSY;

This should also check kvm_is_realm() (otherwise we dereference a NULL
realm).

Correct, I think this should be done way up in the stack at :

kvm_vm_ioctl_enable_cap() for KVM_CAP_ARM_RME.

I was wondering about fuzzing the API to find more of this kind of issue,
but don't know anything about it. Is there a recommended way to fuzz KVM?

Not sure either. kselftests is one possible way to drive these test at 
least for unit-testing the new ABIs. This is something we plan to add.

Thanks for catching this.

Suzuki

Thanks,
Jean

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