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[GIT,PULL,1/1] KVM: s390: Check kvm pointer when testing KVM_CAP_S390_HPAGE_1M

Message ID 20240507122945.2571-2-borntraeger@linux.ibm.com (mailing list archive)
State New
Headers show
Series [GIT,PULL,1/1] KVM: s390: Check kvm pointer when testing KVM_CAP_S390_HPAGE_1M | expand

Commit Message

Christian Borntraeger May 7, 2024, 12:29 p.m. UTC 
From: Jean-Philippe Brucker <jean-philippe@linaro.org>

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@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>
---
 arch/s390/kvm/kvm-s390.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

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: