From: Ido Yariv <ido@wizery.com>
Date: Fri, 21 Oct 2016 16:39:57 +0000 (-0400)
Subject: KVM: x86: fix wbinvd_dirty_mask use-after-free
X-Git-Tag: v3.10.105~288
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a3e49e607d8b858519a83ec65e4aac66ba847f62;p=thirdparty%2Fkernel%2Fstable.git

KVM: x86: fix wbinvd_dirty_mask use-after-free

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: Willy Tarreau <w@1wt.eu>
---

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8e57771d4bfde..fc68806e6f50c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6509,11 +6509,13 @@ void kvm_put_guest_fpu(struct kvm_vcpu *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);
 	fx_free(vcpu);
 	kvm_x86_ops->vcpu_free(vcpu);
+	free_cpumask_var(wbinvd_dirty_mask);
 }
 
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,