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R. Silva" To: Rodrigo Vivi Cc: Jani Nikula , Joonas Lahtinen , Tvrtko Ursulin , David Airlie , Daniel Vetter , intel-gfx@lists.freedesktop.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH][next] drm/i915/guc: Replace zero-length arrays with flexible-array members Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 10, 2023 at 02:28:11PM -0500, Rodrigo Vivi wrote: > > On Tue, Jan 10, 2023 at 10:44:53AM -0600, Gustavo A. R. Silva wrote: > > Zero-length arrays are deprecated[1] and we are moving towards > > adopting C99 flexible-array members, instead. So, replace zero-length > > arrays in a couple of structures (three, actually) with flex-array > > members. > > > > This helps with the ongoing efforts to tighten the FORTIFY_SOURCE > > routines on memcpy() and help us make progress towards globally > > enabling -fstrict-flex-arrays=3 [2]. > > > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1] > > Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2] > > Link: https://github.com/KSPP/linux/issues/78 > > Signed-off-by: Gustavo A. R. Silva > > > --- > > drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h b/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h > > index 3624abfd22d1..9d589c28f40f 100644 > > --- a/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h > > +++ b/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h > > @@ -73,7 +73,7 @@ struct guc_debug_capture_list_header { > > > > struct guc_debug_capture_list { > > struct guc_debug_capture_list_header header; > > - struct guc_mmio_reg regs[0]; > > + struct guc_mmio_reg regs[]; > > } __packed; > > > > /** > > @@ -125,7 +125,7 @@ struct guc_state_capture_header_t { > > > > struct guc_state_capture_t { > > struct guc_state_capture_header_t header; > > - struct guc_mmio_reg mmio_entries[0]; > > + struct guc_mmio_reg mmio_entries[]; > > } __packed; > > > > enum guc_capture_group_types { > > @@ -145,7 +145,7 @@ struct guc_state_capture_group_header_t { > > /* this is the top level structure where an error-capture dump starts */ > > struct guc_state_capture_group_t { > > struct guc_state_capture_group_header_t grp_header; > > - struct guc_state_capture_t capture_entries[0]; > > + struct guc_state_capture_t capture_entries[]; > > Please notice we are currently using sizeof(struct ...). Yep; I noticed that. :) > Along with your proposed changes, shouldn't we also start using > the struct_size() which already take the flexible array into account? Not necessarily. In recent times, we don't include the struct_size changes in the same patch as the flex-array transformation. That's usually a follow-up patch. -- Gustavo