Commit 338c7dba authored Nov 18, 2013 by Andy Honig Committed by Paolo Bonzini Dec 12, 2013

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>

parent 2e7babfa

virt/kvm/kvm_main.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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);

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