From patchwork Tue Feb 11 20:53:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. 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R. Silva" To: Jiri Pirko , Andrew Morton Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] lib: objagg: Replace zero-length arrays with flexible-array member Message-ID: <20200211205356.GA23101@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 200.68.140.36 X-Source-L: No X-Exim-ID: 1j1cV7-001wuz-5G X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.140.36]:15013 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 42 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertenly introduced[3] to the codebase from now on. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Acked-by: Jiri Pirko --- lib/objagg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/objagg.c b/lib/objagg.c index 576be22e86de..668a2c0a88ac 100644 --- a/lib/objagg.c +++ b/lib/objagg.c @@ -28,7 +28,7 @@ struct objagg_hints_node { struct objagg_hints_node *parent; unsigned int root_id; struct objagg_obj_stats_info stats_info; - unsigned long obj[0]; + unsigned long obj[]; }; static struct objagg_hints_node * @@ -66,7 +66,7 @@ struct objagg_obj { * including nested objects */ struct objagg_obj_stats stats; - unsigned long obj[0]; + unsigned long obj[]; }; static unsigned int objagg_obj_ref_inc(struct objagg_obj *objagg_obj)