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KVM: s390: Check kvm pointer when testing KVM_CAP_S390_HPAGE_1M

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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: 40ebdb8e59 ("KVM: s390: Make huge pages unavailable in ucontrol VMs")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Message-ID: <20240419160723.320910-2-jean-philippe@linaro.org>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
This commit is contained in:
Jean-Philippe Brucker 2024-04-19 17:07:24 +01:00 committed by Christian Borntraeger
parent 16c20208b9
commit 175f2f5bcd
1 changed files with 1 additions and 1 deletions
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2
arch/s390/kvm/kvm-s390.c
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@ -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: