[Devel] [PATCH RHEL7 COMMIT] KVM: x86: cleanup the page tracking SRCU instance

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.21.1.vz7.47.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.21.1.vz7.47.2
------>
commit 4fe94d0bd64ca07ae99a79575d78aeb68cf4e104
Author: Paolo Bonzini <pbonzini at redhat.com>
Date:   Fri Apr 27 13:34:50 2018 +0300

    KVM: x86: cleanup the page tracking SRCU instance
    
    SRCU uses a delayed work item.  Skip cleaning it up, and
    the result is use-after-free in the work item callbacks.
    
    Reported-by: Dmitry Vyukov <dvyukov at google.com>
    Suggested-by: Dmitry Vyukov <dvyukov at google.com>
    Cc: stable at vger.kernel.org
    Fixes: 0eb05bf290cfe8610d9680b49abef37febd1c38a
    Reviewed-by: Xiao Guangrong <xiaoguangrong.eric at gmail.com>
    Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
    
    (cherry picked from commit 2beb6dad2e8f95d710159d5befb390e4f62ab5cf)
    Signed-off-by: Roman Kagan <rkagan at virtuozzo.com>
---
 arch/x86/include/asm/kvm_page_track.h | 1 +
 arch/x86/kvm/page_track.c             | 8 ++++++++
 arch/x86/kvm/x86.c                    | 1 +
 3 files changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index d74747b031ec..c4eda791f877 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -46,6 +46,7 @@ struct kvm_page_track_notifier_node {
 };
 
 void kvm_page_track_init(struct kvm *kvm);
+void kvm_page_track_cleanup(struct kvm *kvm);
 
 void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
 				 struct kvm_memory_slot *dont);
diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
index 4a1c13eaa518..c9473acd65d6 100644
--- a/arch/x86/kvm/page_track.c
+++ b/arch/x86/kvm/page_track.c
@@ -158,6 +158,14 @@ bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
 	return !!ACCESS_ONCE(slot->arch.gfn_track[mode][index]);
 }
 
+void kvm_page_track_cleanup(struct kvm *kvm)
+{
+	struct kvm_page_track_notifier_head *head;
+
+	head = &kvm->arch.track_notifier_head;
+	cleanup_srcu_struct(&head->track_srcu);
+}
+
 void kvm_page_track_init(struct kvm *kvm)
 {
 	struct kvm_page_track_notifier_head *head;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5db5b179b47b..265ca677257f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8019,6 +8019,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kvm_free_vcpus(kvm);
 	kvfree(rcu_dereference_check(kvm->arch.apic_map, 1));
 	kvm_mmu_uninit_vm(kvm);
+	kvm_page_track_cleanup(kvm);
 }
 
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,