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([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id x16sm4468819ejj.8.2021.10.06.06.36.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 06 Oct 2021 06:36:21 -0700 (PDT) Message-ID: Date: Wed, 6 Oct 2021 15:36:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH MANUALSEL 5.14 2/9] KVM: x86: Handle SRCU initialization failure during page track init Content-Language: en-US To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Haimin Zhang , TCS Robot , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, kvm@vger.kernel.org References: <20211006133021.271905-1-sashal@kernel.org> <20211006133021.271905-2-sashal@kernel.org> From: Paolo Bonzini In-Reply-To: <20211006133021.271905-2-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/10/21 15:30, Sasha Levin wrote: > From: Haimin Zhang > > [ Upstream commit eb7511bf9182292ef1df1082d23039e856d1ddfb ] > > 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 > Signed-off-by: Haimin Zhang > 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 > Signed-off-by: Sasha Levin > --- > 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(-) > > diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h > index 87bd6025d91d..6a5f3acf2b33 100644 > --- 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); > diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c > index 91a9f7e0fd91..68e67228101d 100644 > --- 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 *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); > } > > /* > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 7ec7c2dce506..b3f855d48f72 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11090,9 +11090,15 @@ 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); > @@ -11125,7 +11131,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > > kvm_apicv_init(kvm); > kvm_hv_init_vm(kvm); > - kvm_page_track_init(kvm); > kvm_mmu_init_vm(kvm); > > return static_call(kvm_x86_vm_init)(kvm); > Acked-by: Paolo Bonzini