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authorAndy Honig <ahonig@google.com>2013-11-18 16:09:22 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2013-12-12 22:39:33 +0100
commit338c7dbadd2671189cec7faf64c84d01071b3f96 (patch)
treef8aa565a09db010f6a5693051197bcb75073108a /virt/kvm/kvm_main.c
parent2e7babfa892a55588467ef03b545002e32f31528 (diff)
downloadlwn-338c7dbadd2671189cec7faf64c84d01071b3f96.tar.gz
lwn-338c7dbadd2671189cec7faf64c84d01071b3f96.zip
KVM: Improve create VCPU parameter (CVE-2013-4587)
In multiple functions the vcpu_id is used as an offset into a bitfield. Ag malicious user could specify a vcpu_id greater than 255 in order to set or clear bits in kernel memory. This could be used to elevate priveges in the kernel. This patch verifies that the vcpu_id provided is less than 255. The api documentation already specifies that the vcpu_id must be less than max_vcpus, but this is currently not checked. Reported-by: Andrew Honig <ahonig@google.com> Cc: stable@vger.kernel.org Signed-off-by: Andrew Honig <ahonig@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm/kvm_main.c')
-rw-r--r--virt/kvm/kvm_main.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a0aa84b5941a..4f588bc94186 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1898,6 +1898,9 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
int r;
struct kvm_vcpu *vcpu, *v;
+ if (id >= KVM_MAX_VCPUS)
+ return -EINVAL;
+
vcpu = kvm_arch_vcpu_create(kvm, id);
if (IS_ERR(vcpu))
return PTR_ERR(vcpu);