From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Date: Tue, 21 Sep 2021 00:05:07 +0000 Subject: Re: [PATCH] KVM: PPC: Replace zero-length array with flexible array member Message-Id: List-Id: References: <20210918142138.17709-1-len.baker@gmx.com> In-Reply-To: <20210918142138.17709-1-len.baker@gmx.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Len Baker , Paul Mackerras , Michael Ellerman , Benjamin Herrenschmidt Cc: "Gustavo A. R. Silva" , Kees Cook , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org On 9/18/21 09:21, Len Baker wrote: > There is a regular need in the kernel to provide a way to declare having > a dynamically sized set of trailing elements in a structure. Kernel code > should always use "flexible array members" [1] for these cases. The > older style of one-element or zero-length arrays should no longer be > used[2]. > > Also, make use of the struct_size() helper in kzalloc(). > > [1] https://en.wikipedia.org/wiki/Flexible_array_member > [2] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > Signed-off-by: Len Baker Reviewed-by: Gustavo A. R. Silva Thanks -- Gustavo > --- > arch/powerpc/include/asm/kvm_host.h | 2 +- > arch/powerpc/kvm/book3s_64_vio.c | 3 +-- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h > index 080a7feb7731..3aed653373a5 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -190,7 +190,7 @@ struct kvmppc_spapr_tce_table { > u64 size; /* window size in pages */ > struct list_head iommu_tables; > struct mutex alloc_lock; > - struct page *pages[0]; > + struct page *pages[]; > }; > > /* XICS components, defined in book3s_xics.c */ > diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c > index 6365087f3160..d42b4b6d4a79 100644 > --- a/arch/powerpc/kvm/book3s_64_vio.c > +++ b/arch/powerpc/kvm/book3s_64_vio.c > @@ -295,8 +295,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, > return ret; > > ret = -ENOMEM; > - stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *), > - GFP_KERNEL); > + stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL); > if (!stt) > goto fail_acct; > > -- > 2.25.1 >