From: Steve Rutherford <srutherford@xxxxxxxxxx>
[ Upstream commit 7289fdb5dcdbc5155b5531529c44105868a762f2 ]
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: Jon Cargille <jcargill@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Message-Id: <20200416191152.259434-1-jcargill@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 61fc92f92e0a0..ef920da075184 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4013,10 +4013,13 @@ 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: {
@@ -4036,10 +4039,13 @@ 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: {
--
2.25.1
