diff options
| author | Steve Rutherford <srutherford@google.com> | 2020-04-16 12:11:52 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-01 13:12:41 +0200 |
| commit | f81fe6eb5b2e02f993f11170dcaf3d4f2a41b3c8 (patch) | |
| tree | 38e4584cbdfcee6243c7ff1bd7da36f330a211dd | |
| parent | 10f556247876d1db19bb3cdfb9b9333ef95cf805 (diff) | |
KVM: Remove CREATE_IRQCHIP/SET_PIT2 race
[ 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@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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/x86/kvm/x86.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3aed03942d7d..79fa55de635c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4370,10 +4370,13 @@ 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: { @@ -4393,10 +4396,13 @@ 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: { |