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From: Hydro Flask <hydroflask@yqxmail.com>
To: musl@lists.openwall.com
Subject: [musl] Potential deadlock in pthread_kill()
Date: Mon, 29 Jun 2020 21:19:08 -0700	[thread overview]
Message-ID: <0217b8838100175725993b0ed0114ee7@thelig.ht> (raw)

Hello all,

Noticed something while reading some code today. pthread_kill() is 
specified by POSIX to be async signal safe but I noticed that in musl's 
implementation if a signal occurs while the "killlock" is held and the 
signal handler calls pthread_kill() on the same target thread, a 
deadlock will occur. Is this intentional?

         int pthread_kill(pthread_t t, int sig)
         {
                 int r;
                 LOCK(t->killlock);
                 r = t->tid ? -__syscall(SYS_tkill, t->tid, sig)
                         : (sig+0U >= _NSIG ? EINVAL : 0);
                 UNLOCK(t->killlock);
                 return r;
         }

Thank you for your attention.

Hydro

             reply	other threads:[~2020-06-30  4:19 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30  4:19 Hydro Flask [this message]
2020-06-30  4:43 ` Rich Felker
2020-06-30  6:19   ` Hydro Flask
2020-06-30  9:26     ` Rich Felker
2020-06-30 14:58       ` Markus Wichmann
2020-06-30 16:28         ` Hydro Flask
2020-06-30 19:28           ` Dmitry Samersoff
2020-06-30 19:54             ` Rich Felker
2020-06-30 21:00               ` Hydro Flask
2020-07-06 22:00                 ` Rich Felker
2020-07-06 22:14                   ` Hydro Flask
2020-07-06 22:22                     ` Rich Felker
2020-07-06 22:37                       ` Hydro Flask

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