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Message-ID: <20230212200425.GP4163@brightrain.aerifal.cx>
Date: Sun, 12 Feb 2023 15:04:26 -0500
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [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
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