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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id a20sm5606772pjh.46.2021.09.03.09.18.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Sep 2021 09:18:45 -0700 (PDT) Date: Fri, 3 Sep 2021 16:18:41 +0000 From: Sean Christopherson To: tcs.kernel@gmail.com Cc: pbonzini@redhat.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, jarkko@kernel.org, Haimin Zhang Subject: Re: [PATCH v2] KVM: x86: Handle SRCU initialization failure during page track init Message-ID: References: <1630636626-12262-1-git-send-email-tcs_kernel@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1630636626-12262-1-git-send-email-tcs_kernel@tencent.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Sep 03, 2021, tcs.kernel@gmail.com wrote: > From: Haimin Zhang > > 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. > > Signed-off-by: Haimin Zhang > Signed-off-by: Sean Christopherson > Signed-off-by: Vitaly Kuznetsov Neither myself nor Vitaly provided an SOB, nor is one needed. Review feedback can be attributed/noted in the part that git ignores (below the three dashes). > Reported-by: TCS Robot > > --- Notes about version changes, e.g. to document/attribute review feedback, go here. v2: - Blah blah blah [Vitaly, Sean] > arch/x86/include/asm/kvm_page_track.h | 2 +- > arch/x86/kvm/mmu/page_track.c | 4 ++-- > arch/x86/kvm/x86.c | 6 +++++- > 3 files changed, 8 insertions(+), 4 deletions(-) > ... > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 86539c1..9a122af 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11143,6 +11143,8 @@ 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; > > @@ -11178,7 +11180,9 @@ 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); > + ret = kvm_page_track_init(kvm); > + if (ret) > + return ret; Before moving forward with a fix, I'd like to get Paolo's input on dropping track_srcu in favor of kvm->srcu and avoiding this altogheter. Note, Paolo is on vacation at the moment, so this won't get attention for a week or more. [*] https://lkml.kernel.org/r/YS5Bn6I6wVEL8wKS@google.com > kvm_mmu_init_vm(kvm); > kvm_xen_init_vm(kvm); > > -- > 1.8.3.1 >