From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on sa.local.altlinux.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 Date: Thu, 11 Jul 2019 21:22:35 +0200 From: Alexey Gladkov To: Vladislav Ivanishin Message-ID: <20190711192235.GH19890@Legion-PC.fortress> References: <87v9xcugq3.fsf@ispras.ru> <87ef2wxxbu.fsf@ispras.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87ef2wxxbu.fsf@ispras.ru> Cc: kbd@lists.altlinux.org Subject: Re: [kbd] [Lint][Bug report] src/openvt.c:386: 'pid' may be used uninitialized X-BeenThere: kbd@lists.altlinux.org X-Mailman-Version: 2.1.12 Precedence: list Reply-To: Linux console tools development discussion List-Id: Linux console tools development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Jul 2019 19:22:40 -0000 Archived-At: List-Archive: On Thu, Jul 11, 2019 at 09:03:49PM +0300, Vladislav Ivanishin wrote: > Sorry, I didn't get your reply (not sure what the actual reason is, but > it seems as if you've only replied to the list, and I am not subscribed) > so I've just read it today in the archives. > > > On Tue, Jun 11, 2019 at 09:20:04PM +0300, Vladislav Ivanishin wrote: > > > Hi, > > > > > > I've found this bug using a static analyzer (slightly improved GCC). > > > > > > Consider variable `pid` in function main from src/openvt.c: > > > > > > src/openvt.c:166: int opt, pid, i; > > > src/openvt.c:303: if (direct_exec || ((pid = fork()) == 0)) { > > > src/openvt.c:386: if (pid < 0) > > > src/openvt.c:393: waitpid(pid, &retval, 0); > > > > > > If direct_exec is TRUE, then pid doesn't get initialized, but it is used > > > outside the conditional regardless of that. > > > > This is not a bug. If direct_exec is TRUE we will never be on line 386. > > Oh, I didn't realize that; my bad, thanks for pointing this out. > > The real issue preventing the analyzer (i.e. the compiler) from seeing > this as well is kbd_error lacking the noreturn attribute. > > > To make linter happy, I’ll make pid = 0. > > So a more proper fix would be adding the attribute in the header file. > It would also make other compiler analyses/optimizations more effective. I already did it recently: https://github.com/legionus/kbd/commit/93689a202aeae8707c59c67aa1af5a36c27fba6c -- Rgrds, legion