From 175f2f5bcdfce9e728f1ff956a50f28824d28791 Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Fri, 19 Apr 2024 17:07:24 +0100 Subject: [PATCH] KVM: s390: Check kvm pointer when testing KVM_CAP_S390_HPAGE_1M 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 Reviewed-by: Claudio Imbrenda Reviewed-by: Christian Borntraeger Message-ID: <20240419160723.320910-2-jean-philippe@linaro.org> Signed-off-by: Christian Borntraeger --- 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 5147b943a864..7721eb522f43 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: