From: Steve Rutherford <srutherford@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Peter Shier <pshier@xxxxxxxxxx>
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 506bd2b4b8bb7..188bc3fc907f1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4518,10 +4518,11 @@ 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;
- r = kvm_vm_ioctl_set_pit(kvm, &u.ps);
+ if (kvm->arch.vpit)
+ r = kvm_vm_ioctl_set_pit(kvm, &u.ps);
+ mutex_unlock(&kvm->lock);
break;
}
case KVM_GET_PIT2: {
@@ -4541,10 +4542,11 @@ 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;
- r = kvm_vm_ioctl_set_pit2(kvm, &u.ps2);
+ if (kvm->arch.vpit)
+ r = kvm_vm_ioctl_set_pit2(kvm, &u.ps2);
+ mutex_unlock(&kvm->lock);
break;
}
case KVM_REINJECT_CONTROL: {
--
2.19.0.rc0.228.g281dcd1b4d0-goog
