Patch "KVM: x86: fix wbinvd_dirty_mask use-after-free" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

KVM: x86: fix wbinvd_dirty_mask use-after-free

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-x86-fix-wbinvd_dirty_mask-use-after-free.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ido Yariv <[email protected]>
Date: Fri, 21 Oct 2016 12:39:57 -0400
Subject: KVM: x86: fix wbinvd_dirty_mask use-after-free
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From: Ido Yariv <[email protected]>

commit bd768e146624cbec7122ed15dead8daa137d909d upstream.

vcpu->arch.wbinvd_dirty_mask may still be used after freeing it, corrupting memory. For example, the following call trace may set a bit in an already freed cpu mask:
kvm_arch_vcpu_load
vcpu_load
vmx_free_vcpu_nested
vmx_free_vcpu
kvm_arch_vcpu_free

Fix this by deferring freeing of wbinvd_dirty_mask.

---
 arch/x86/kvm/x86.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -7252,10 +7252,12 @@ void kvm_put_guest_fpu(struct kvm_vcpu *
 
 void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
 {
+	void *wbinvd_dirty_mask = vcpu->arch.wbinvd_dirty_mask;
+
 	kvmclock_reset(vcpu);
 
-	free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);
 	kvm_x86_ops->vcpu_free(vcpu);
+	free_cpumask_var(wbinvd_dirty_mask);
 }
 
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/kvm-x86-fix-wbinvd_dirty_mask-use-after-free.patch