ARM: KVM: prevent NULL pointer dereferences with KVM VCPU ioctl
Some ARM KVM VCPU ioctls require the vCPU to be properly initialized
with the KVM_ARM_VCPU_INIT ioctl before being used with further
requests. KVM_RUN checks whether this initialization has been
done, but other ioctls do not.
Namely KVM_GET_REG_LIST will dereference an array with index -1
without initialization and thus leads to a kernel oops.
Fix this by adding checks before executing the ioctl handlers.
[ Removed superflous comment from static function - Christoffer ]
Changes from v1:
* moved check into a static function with a meaningful name
Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 37d216d..ef1703b 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -492,6 +492,11 @@
wait_event_interruptible(*wq, !vcpu->arch.pause);
}
+static int kvm_vcpu_initialized(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.target >= 0;
+}
+
/**
* kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
* @vcpu: The VCPU pointer
@@ -508,8 +513,7 @@
int ret;
sigset_t sigsaved;
- /* Make sure they initialize the vcpu with KVM_ARM_VCPU_INIT */
- if (unlikely(vcpu->arch.target < 0))
+ if (unlikely(!kvm_vcpu_initialized(vcpu)))
return -ENOEXEC;
ret = kvm_vcpu_first_run_init(vcpu);
@@ -710,6 +714,10 @@
case KVM_SET_ONE_REG:
case KVM_GET_ONE_REG: {
struct kvm_one_reg reg;
+
+ if (unlikely(!kvm_vcpu_initialized(vcpu)))
+ return -ENOEXEC;
+
if (copy_from_user(®, argp, sizeof(reg)))
return -EFAULT;
if (ioctl == KVM_SET_ONE_REG)
@@ -722,6 +730,9 @@
struct kvm_reg_list reg_list;
unsigned n;
+ if (unlikely(!kvm_vcpu_initialized(vcpu)))
+ return -ENOEXEC;
+
if (copy_from_user(®_list, user_list, sizeof(reg_list)))
return -EFAULT;
n = reg_list.n;