openssh unix dev - Jan 2022 - OS X poll breakage (Was: Please help test recent changes)

On Fri, Jan 07, 2022 at 09:52:09AM +1100, Damien Miller
wrote:
> 1. Conversion of the ssh and sshd mainloop from select() to poll()
> 
> This should be entirely invisible to users, so any behaviour change
> is a bug. If you see something and want to help debug it further,
> uncomment the DEBUG_CHANNEL_POLL #define in channels.c for helps of
> extra debug logging.
This change breaks (at least) the exit-status test on Mac OS X.  I
haven't had a chance to investigate yet,

$ git bisect run sh -c "autoreconf && ./configure --without-openssl
&&
make t-exec LTESTS=exit-status"
[... lots ...]
17877bc81db3846e6e7d4cfb124d966bb9c9296b is the first bad commit
commit 17877bc81db3846e6e7d4cfb124d966bb9c9296b
Author: djm at openbsd.org <djm at openbsd.org>
Date:   Thu Jan 6 21:48:38 2022 +0000

    upstream: convert ssh, sshd mainloops from select() to poll();

    feedback & ok deraadt@ and markus@ has been in snaps for a few months

    OpenBSD-Commit-ID: a77e16a667d5b194dcdb3b76308b8bba7fa7239c

$ uname -a
Darwin osx-highsierra 17.7.0 Darwin Kernel Version 17.7.0: Fri Oct 30
13:34:27 PDT 2020; root:xnu-4570.71.82.8~1/RELEASE_X86_64 x86_64

-- 
Darren Tucker (dtucker at dtucker.net)
GPG key 11EAA6FA / A86E 3E07 5B19 5880 E860  37F4 9357 ECEF 11EA A6FA (new)
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

On Mon, 10 Jan 2022, Darren Tucker wrote:
> On Fri, Jan 07, 2022 at 09:52:09AM +1100, Damien Miller wrote:
> > 1. Conversion of the ssh and sshd mainloop from select() to poll()
> > 
> > This should be entirely invisible to users, so any behaviour change
> > is a bug. If you see something and want to help debug it further,
> > uncomment the DEBUG_CHANNEL_POLL #define in channels.c for helps of
> > extra debug logging.
> 
> This change breaks (at least) the exit-status test on Mac OS X.  I
> haven't had a chance to investigate yet,
> 
> $ git bisect run sh -c "autoreconf && ./configure
--without-openssl &&
> make t-exec LTESTS=exit-status"
> [... lots ...]
> 17877bc81db3846e6e7d4cfb124d966bb9c9296b is the first bad commit
> commit 17877bc81db3846e6e7d4cfb124d966bb9c9296b
> Author: djm at openbsd.org <djm at openbsd.org>
> Date:   Thu Jan 6 21:48:38 2022 +0000
> 
>     upstream: convert ssh, sshd mainloops from select() to poll();
> 
>     feedback & ok deraadt@ and markus@ has been in snaps for a few
months
> 
>     OpenBSD-Commit-ID: a77e16a667d5b194dcdb3b76308b8bba7fa7239c
> 
> $ uname -a
> Darwin osx-highsierra 17.7.0 Darwin Kernel Version 17.7.0: Fri Oct 30
> 13:34:27 PDT 2020; root:xnu-4570.71.82.8~1/RELEASE_X86_64 x86_64
Here's the client side log of the failure. It comes from the
"same with early close of stdout/err" section of the test, but I
can't
actually see anything get closed...

debug3: receive packet: type 91
debug2: channel_input_open_confirmation: channel 0: callback start
debug2: client_session2_setup: id 0
debug1: Sending command: exec sh -c 'sleep 2; exec > /dev/null
2>&1; sleep 3; exit 0'
debug2: channel 0: request exec confirm 1
debug3: send packet: type 98
debug2: channel_input_open_confirmation: channel 0: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel 0: rcvd adjust 2097152
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: exec request accepted on channel 0
channel 0: invalid rfd pollfd[2].fd 4 r4 w7 e8 s-1

and (separate run) with DEBUG_CHANNEL_POLL set:

debug2: channel_input_status_confirm: type 99 id 0
debug2: exec request accepted on channel 0
debug3: dump_channel_poll: channel 0: rfd r4 w7 e8 s-1 pfd[2].fd=4 want 0x01 ev
0x01 ready 0x00 rev 0x00
debug3: dump_channel_poll: channel 0: rfd r4 w7 e8 s-1 pfd[3].fd=7 want 0x01 ev
0x00 ready 0x00 rev 0x00
debug3: dump_channel_poll: channel 0: rfd r4 w7 e8 s-1 pfd[4].fd=8 want 0x01 ev
0x00 ready 0x00 rev 0x00
debug1: channel_after_poll: pfd[2].fd 4 rev 0x0020
debug3: dump_channel_poll: channel 0: rfd r4 w7 e8 s-1 pfd[2].fd=4 want 0x01 ev
0x01 ready 0x00 rev 0x20
channel 0: invalid rfd pollfd[2].fd 4 r4 w7 e8 s-1
FAIL: exit code (with sleep) mismatch for: 255 != 0

It looks like it fails with HAVE_POLL set to 0 too.

Still looking...

-d