Commit 7289fdb5 authored Apr 16, 2020 by Steve Rutherford Committed by Paolo Bonzini Apr 17, 2020

KVM: Remove CREATE_IRQCHIP/SET_PIT2 race



Fixes a NULL pointer dereference, caused by the PIT firing an interrupt
before the interrupt table has been initialized.

SET_PIT2 can race with the creation of the IRQchip. In particular,
if SET_PIT2 is called with a low PIT timer period (after the creation of
the IOAPIC, but before the instantiation of the irq routes), the PIT can
fire an interrupt at an uninitialized table.

Signed-off-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Jon Cargille <jcargill@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200416191152.259434-1-jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 56a87e5d

arch/x86/kvm/x86.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -5049,10 +5049,13 @@ set_identity_unlock:
		r = -EFAULT;
		if (copy_from_user(&u.ps, argp, sizeof(u.ps)))
		goto out;
		mutex_lock(&kvm->lock);
		r = -ENXIO;
		if (!kvm->arch.vpit)
		goto out;
		goto set_pit_out;
		r = kvm_vm_ioctl_set_pit(kvm, &u.ps);
		set_pit_out:
		mutex_unlock(&kvm->lock);
		break;
		}
		case KVM_GET_PIT2: {
		@@ -5072,10 +5075,13 @@ set_identity_unlock:
		r = -EFAULT;
		if (copy_from_user(&u.ps2, argp, sizeof(u.ps2)))
		goto out;
		mutex_lock(&kvm->lock);
		r = -ENXIO;
		if (!kvm->arch.vpit)
		goto out;
		goto set_pit2_out;
		r = kvm_vm_ioctl_set_pit2(kvm, &u.ps2);
		set_pit2_out:
		mutex_unlock(&kvm->lock);
		break;
		}
		case KVM_REINJECT_CONTROL: {

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