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Commit 3633031d authored by Radim Krčmář's avatar Radim Krčmář
Browse files

Merge tag 'kvm-s390-master-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux 

KVM: s390: Fix for user-triggerable WARN_ON

A malicious user space can provide an invalid mode for runtime
instrumentation via the interfaces that are normally used on
the target host during migration. This would trigger a WARN_ON
via validity intercept. Let's detect this special case.
parents f6bbf1b7 a5efb6b6

arch/s390/kvm/intercept.c

+7 −2
Original line number Diff line number Diff line
@@ -119,8 +119,13 @@ static int handle_validity(struct kvm_vcpu *vcpu) 


	vcpu->stat.exit_validity++;

	trace_kvm_s390_intercept_validity(vcpu, viwhy);

	WARN_ONCE(true, "kvm: unhandled validity intercept 0x%x\n", viwhy);

	return -EOPNOTSUPP;

	KVM_EVENT(3, "validity intercept 0x%x for pid %u (kvm 0x%pK)", viwhy,

		  current->pid, vcpu->kvm);



	/* do not warn on invalid runtime instrumentation mode */

	WARN_ONCE(viwhy != 0x44, "kvm: unhandled validity intercept 0x%x\n",

		  viwhy);

	return -EINVAL;

}



static int handle_instruction(struct kvm_vcpu *vcpu)