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Sat, 26 Mar 2022 22:16:55 -0700 (PDT) Received: from localhost.localdomain ([115.220.243.108]) by smtp.googlemail.com with ESMTPSA id d11-20020a056a00198b00b004fa7da68465sm11290361pfl.60.2022.03.26.22.16.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Mar 2022 22:16:55 -0700 (PDT) From: Xiaomeng Tong To: mpe@ellerman.id.au Subject: [PATCH] kvm: fix incorrect NULL check on list iterator Date: Sun, 27 Mar 2022 13:16:46 +0800 Message-Id: <20220327051646.1856-1-xiam0nd.tong@gmail.com> X-Mailer: git-send-email 2.17.1 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: david@redhat.com, maz@kernel.org, Felix.Kuehling@amd.com, apopple@nvidia.com, linuxram@us.ibm.com, linux-kernel@vger.kernel.org, liam.howlett@oracle.com, bharata@linux.ibm.com, paulus@samba.org, stable@vger.kernel.org, Xiaomeng Tong , akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, maciej.szmigiero@oracle.com Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" The bug is here: if (!p) return ret; The list iterator value 'p' will *always* be set and non-NULL by list_for_each_entry(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element is found. To fix the bug, Use a new value 'iter' as the list iterator, while use the old value 'p' as a dedicated variable to point to the found element. Cc: stable@vger.kernel.org Fixes: dfaa973ae9605 ("KVM: PPC: Book3S HV: In H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs") Signed-off-by: Xiaomeng Tong --- arch/powerpc/kvm/book3s_hv_uvmem.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index e414ca44839f..0cb20ee6a632 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -360,13 +360,15 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm, static bool kvmppc_next_nontransitioned_gfn(const struct kvm_memory_slot *memslot, struct kvm *kvm, unsigned long *gfn) { - struct kvmppc_uvmem_slot *p; + struct kvmppc_uvmem_slot *p = NULL, *iter; bool ret = false; unsigned long i; - list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) - if (*gfn >= p->base_pfn && *gfn < p->base_pfn + p->nr_pfns) + list_for_each_entry(iter, &kvm->arch.uvmem_pfns, list) + if (*gfn >= iter->base_pfn && *gfn < iter->base_pfn + iter->nr_pfns) { + p = iter; break; + } if (!p) return ret; /*