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KVM: x86: Handle SRCU initialization failure during page track init

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commit eb7511bf9182292ef1df1082d23039e856d1ddfb upstream.

Check the return of init_srcu_struct(), which can fail due to OOM, when
initializing the page track mechanism.  Lack of checking leads to a NULL
pointer deref found by a modified syzkaller.

Reported-by: TCS Robot <tcs_robot@tencent.com>
Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
Message-Id: <1630636626-12262-1-git-send-email-tcs_kernel@tencent.com>
[Move the call towards the beginning of kvm_arch_init_vm. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Haimin Zhang 2021-09-03 10:37:06 +08:00 committed by Greg Kroah-Hartman
parent f7ac4d24e1
commit deb2949417
3 changed files with 9 additions and 4 deletions
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2
arch/x86/include/asm/kvm_page_track.h
View File

@ -46,7 +46,7 @@ struct kvm_page_track_notifier_node {
struct kvm_page_track_notifier_node *node);
};
void kvm_page_track_init(struct kvm *kvm);
int 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 *slot);

4
arch/x86/kvm/mmu/page_track.c
View File

@ -163,13 +163,13 @@ void kvm_page_track_cleanup(struct kvm *kvm)
cleanup_srcu_struct(&head->track_srcu);
}
void kvm_page_track_init(struct kvm *kvm)
int kvm_page_track_init(struct kvm *kvm)
{
struct kvm_page_track_notifier_head *head;
head = &kvm->arch.track_notifier_head;
init_srcu_struct(&head->track_srcu);
INIT_HLIST_HEAD(&head->track_notifier_list);
return init_srcu_struct(&head->track_srcu);
}
/*

7
arch/x86/kvm/x86.c
View File

@ -10392,9 +10392,15 @@ void kvm_arch_free_vm(struct kvm *kvm)
int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
int ret;
if (type)
return -EINVAL;
ret = kvm_page_track_init(kvm);
if (ret)
return ret;
INIT_HLIST_HEAD(&kvm->arch.mask_notifier_list);
INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);
@ -10421,7 +10427,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);
kvm_hv_init_vm(kvm);
kvm_page_track_init(kvm);
kvm_mmu_init_vm(kvm);
return kvm_x86_ops.vm_init(kvm);