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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>
This commit is contained in:
Steve Rutherford 2020-04-16 12:11:52 -07:00 committed by Paolo Bonzini
parent 56a87e5d99
commit 7289fdb5dc
1 changed files with 8 additions and 2 deletions
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10
arch/x86/kvm/x86.c
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@ -5049,10 +5049,13 @@ long kvm_arch_vm_ioctl(struct file *filp,
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 @@ long kvm_arch_vm_ioctl(struct file *filp,
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: {