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Date:      Sat, 14 Apr 2018 19:42:45 +0000
From:      bugzilla-noreply@freebsd.org
To:        bugs@FreeBSD.org
Subject:   [Bug 227285] File descriptor passing does not work reliably on SMP system
Message-ID:  <bug-227285-227-IoNRA3GtJ1@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-227285-227@https.bugs.freebsd.org/bugzilla/>
References:  <bug-227285-227@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D227285

Jan Kokem=C3=BCller <jan.kokemueller@gmail.com> changed:

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--- Comment #6 from Jan Kokem=C3=BCller <jan.kokemueller@gmail.com> ---
Created attachment 192514
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D192514&action=
=3Dedit
test program (faster reproduction)

Here is a better test program that should uncover the race in a few seconds=
 at
most. Compile with "cc fdpass-race-fast.c -pthread -lnv". I'm spawning anot=
her
thread that just creates and closes socketpairs. This triggers the unp garb=
age
collector constantly.

I believe the race is in soreceive_generic() in sys/kern/uipc_socket.c. The=
 "in
flight" domain socket is taken off the so_rcv sockbuf, but it is not
externalized yet (dom_externalize() hasn't been called). This leads to the =
GC
thinking that the socket is still "in flight" but it doesn't actually get
marked because it is off the so_rcv sockbuf. Now the GC thinks this socket =
is
unreachable and closes it.

--=20
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