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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id t1-20020a63b701000000b005776446f7cbsm4589302pgf.66.2023.10.14.19.29.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Oct 2023 19:29:57 -0700 (PDT) Date: Sat, 14 Oct 2023 19:29:57 -0700 From: Kees Cook To: Christophe JAILLET Cc: Pravin B Shelar , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "Gustavo A. R. Silva" , Nathan Chancellor , Nick Desaulniers , Tom Rix , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, netdev@vger.kernel.org, dev@openvswitch.org, linux-hardening@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v2 2/2] net: openvswitch: Annotate struct mask_array with __counted_by Message-ID: <202310141928.23985F1CA@keescook> References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Sat, Oct 14, 2023 at 08:34:53AM +0200, Christophe JAILLET wrote: > Prepare for the coming implementation by GCC and Clang of the __counted_by > attribute. Flexible array members annotated with __counted_by can have > their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS > (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > functions). > > Signed-off-by: Christophe JAILLET > --- > v2: Fix the subject [Ilya Maximets] > fix the field name used with __counted_by [Ilya Maximets] > > v1: https://lore.kernel.org/all/f66ddcf1ef9328f10292ea75a17b584359b6cde3.1696156198.git.christophe.jaillet@wanadoo.fr/ > > > This patch is part of a work done in parallel of what is currently worked > on by Kees Cook. > > My patches are only related to corner cases that do NOT match the > semantic of his Coccinelle script[1]. > > In this case, in tbl_mask_array_alloc(), several things are allocated with > a single allocation. Then, some pointer arithmetic computes the address of > the memory after the flex-array. > > [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci > --- > net/openvswitch/flow_table.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/openvswitch/flow_table.h b/net/openvswitch/flow_table.h > index 9e659db78c05..f524dc3e4862 100644 > --- a/net/openvswitch/flow_table.h > +++ b/net/openvswitch/flow_table.h > @@ -48,7 +48,7 @@ struct mask_array { > int count, max; > struct mask_array_stats __percpu *masks_usage_stats; > u64 *masks_usage_zero_cntr; > - struct sw_flow_mask __rcu *masks[]; > + struct sw_flow_mask __rcu *masks[] __counted_by(max); > }; Yup, this looks correct to me. Thanks! Reviewed-by: Kees Cook -- Kees Cook