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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From bd768e146624cbec7122ed15dead8daa137d909d Mon Sep 17 00:00:00 2001
From: Ido Yariv <ido@wizery.com>
Date: Fri, 21 Oct 2016 12:39:57 -0400
Subject: KVM: x86: fix wbinvd_dirty_mask use-after-free
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Ido Yariv <ido@wizery.com>

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.

Signed-off-by: Ido Yariv <ido@wizery.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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 ido@wizery.com are

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