From: Haimin Zhang tcs_kernel@tencent.com
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 --- arch/x86/include/asm/kvm_page_track.h | 2 +- arch/x86/kvm/mmu/page_track.c | 4 ++-- arch/x86/kvm/x86.c | 7 ++++++- 3 files changed, 9 insertions(+), 4 deletions(-)
--- a/arch/x86/include/asm/kvm_page_track.h +++ b/arch/x86/include/asm/kvm_page_track.h @@ -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); --- a/arch/x86/kvm/mmu/page_track.c +++ b/arch/x86/kvm/mmu/page_track.c @@ -163,13 +163,13 @@ void kvm_page_track_cleanup(struct 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); }
/* --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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, un 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);