From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_MSPIKE_H2 autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 23248 invoked from network); 12 Feb 2023 20:04:43 -0000 Received: from second.openwall.net (193.110.157.125) by inbox.vuxu.org with ESMTPUTF8; 12 Feb 2023 20:04:43 -0000 Received: (qmail 3903 invoked by uid 550); 12 Feb 2023 20:04:40 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 3868 invoked from network); 12 Feb 2023 20:04:39 -0000 Date: Sun, 12 Feb 2023 15:04:26 -0500 From: Rich Felker To: musl@lists.openwall.com Message-ID: <20230212200425.GP4163@brightrain.aerifal.cx> References: <2da3840a9345c0a810e9d93ab4f6bca7@ispras.ru> <20230211175948.GK4163@brightrain.aerifal.cx> <20230211183505.GL4163@brightrain.aerifal.cx> <20230211194950.GN4163@brightrain.aerifal.cx> <4408deeb62fe668bf720d3c6c8bedda2@ispras.ru> <20230212003158.GO4163@brightrain.aerifal.cx> <0ca8c83af81250f74b609513409669b4@ispras.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] [PATCH] mq_notify: fix close/recv race on failure path On Sun, Feb 12, 2023 at 10:35:39PM +0300, Alexey Izbyshev wrote: > On 2023-02-12 21:23, Alexey Izbyshev wrote: > >On 2023-02-12 03:32, Rich Felker wrote: > >diff --git a/src/mq/mq_notify.c b/src/mq/mq_notify.c > >index a42888d2..8eac71ed 100644 > >--- a/src/mq/mq_notify.c > >+++ b/src/mq/mq_notify.c > >@@ -10,6 +10,8 @@ > > struct args { > > sem_t sem; > > int sock; > >+ mqd_t mqd; > >+ int err; > > const struct sigevent *sev; > > }; > > > >@@ -21,8 +23,21 @@ static void *start(void *p) > > int s = args->sock; > > void (*func)(union sigval) = args->sev->sigev_notify_function; > > union sigval val = args->sev->sigev_value; > >+ struct sigevent sev2; > >+ static const char zeros[32]; > >+ int err = 0; > > > >+ sev2.sigev_notify = SIGEV_THREAD; > >+ sev2.sigev_signo = s; > >+ sev2.sigev_value.sival_ptr = (void *)&zeros; > >+ > >+ err = 0; > > > >This assignment is redundant. > > > >Maybe this hunk could be simplified by getting rid of err and simply > >doing "args->err = -__syscall(SYS_mq_notify, args->mqd, &sev2)". > > > Never mind, err is needed because we can't access args->err after > sem_post. Yep. I'll still switch to __syscall and get rid of the redundant initialization but err is needed since we can't access args later. Rich