openssh bugs - Mar 2022 - [Bug 3410] New: Since 8.9p1 MaxStartups >=1024, in sshd_config, causes "error: ppoll: Invalid argument"

https://bugzilla.mindrot.org/show_bug.cgi?id=3410

            Bug ID: 3410
           Summary: Since 8.9p1 MaxStartups >=1024, in sshd_config, causes
                    "error: ppoll: Invalid argument"
           Product: Portable OpenSSH
           Version: 8.9p1
          Hardware: amd64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: sshd
          Assignee: unassigned-bugs at mindrot.org
          Reporter: for.github.20200406 at gmx.de

Up to 8.8p1 a value of 4096 for MaxStartups in sshd_config was no
problem.
Since 8.9p1 switched to usage of ppoll(2) the maximum value for
MaxStartups is 1023.

Because this is default ppoll(2) behavior, the expected behavior of
sshd would be:
- the documentation should be updated
- sshd -t should show MaxStartups > 1023 as problem (would have saved
me some time, to identify MaxStartups as problem)
- maybe a MaxStartups > 1023 should be reduced to 1023 internally

PS: Maybe setting such a high value for MaxStartups is the wrong
approach for e.g. allowing a massive threaded app access via ssh, but
it was a working solution (in reality, I had a problem with ~100
unauthenticated connections, setting it to 1023 will be good enough).

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https://bugzilla.mindrot.org/show_bug.cgi?id=3410

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
                 CC|                            |djm at mindrot.org
             Blocks|                            |3395

--- Comment #1 from Damien Miller <djm at mindrot.org> ---
This was fixed shortly after release in git master and the V_8_9 stable
branch:

commit 238ac091dd57316bc9690d9cc42229fe21ce0def
Author: djm at openbsd.org <djm at openbsd.org>
Date:   Tue Mar 1 01:59:19 2022 +0000

    upstream: pack pollfd array before server_accept_loop() ppoll()

    call, and terminate sshd if ppoll() returns errno==EINVAL

    avoids spin in ppoll when MaxStartups > RLIMIT_NOFILE, reported by
    Daniel Micay

    feedback/ok deraadt

    OpenBSD-Commit-ID: dbab1c24993ac977ec24d83283b8b7528f7c2c15


Referenced Bugs:

https://bugzilla.mindrot.org/show_bug.cgi?id=3395
[Bug 3395] Tracking bug for openssh-9.0
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https://bugzilla.mindrot.org/show_bug.cgi?id=3410

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

--- Comment #2 from Damien Miller <djm at mindrot.org> ---
closing bug resolved during openssh-9.0 release cycle

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