KVM allows issuing the KVM_CHECK_EXTENSION ioctl either on the /dev/kvm fd or the VM fd. In the first case, kvm_vm_ioctl_check_extension() is called with kvm==NULL. Ensure we don't dereference the pointer in that case. Fixes: 40ebdb8e59df ("KVM: s390: Make huge pages unavailable in ucontrol VMs") Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> --- Only build-tested --- arch/s390/kvm/kvm-s390.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 5147b943a864a..7721eb522f43d 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -587,7 +587,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) break; case KVM_CAP_S390_HPAGE_1M: r = 0; - if (hpage && !kvm_is_ucontrol(kvm)) + if (hpage && !(kvm && kvm_is_ucontrol(kvm))) r = 1; break; case KVM_CAP_S390_MEM_OP: -- 2.44.0