Bug 3071

Summary:

unhandled EINTR while connecting causes ssh to exit prematurely

Product:

Portable OpenSSH

Reporter:

Matthew Avery <mavery>

Component:

ssh

Assignee:

Assigned to nobody <unassigned-bugs>

Status:

CLOSED FIXED

Severity:

trivial

CC:

djm, dtucker

Priority:

Version:

8.0p1

Hardware:

amd64

OS:

Linux

Bug Depends on:

Bug Blocks:

3162

Attachments:

Description	Flags
misc.c path	none
handle EINTR in connect_timeout() and waitfd()	dtucker: ok+

Description Matthew Avery 2019-09-17 03:40:41 AEST

Created attachment 3329 [details]
misc.c path

We've observed some machines always returning one EINTR during a connection where a ConectTimeout is specified on the command line. ssh exits prematurely as the errno == EINTR is processed as hard error instead of being filtered out and retried in the select loop.

It looks to be correlated to migrating to Ubuntu 18.04.4 but the change is trivial enough I didn't dig much further into why it's happening.

patch (attached) is trivial.

web diff of the patch:

https://github.com/matthewaveryusa/openssh-portable/commit/127093f0a177bc4f5316453f777582f113fe18d9#diff-d93946eccdb07e73380c55caff5625f9

-Matt

Comment 1 Damien Miller 2020-05-29 15:16:49 AEST

Created attachment 3401 [details]
handle EINTR in connect_timeout() and waitfd()

I think the timeout_connect() case in the previous patch is slightly wrong. The connect() call did not succeed and needs to be retried.

Darren, is this even necessary with your recent signal changes?

Comment 2 Darren Tucker 2020-05-29 15:37:53 AEST

(In reply to Damien Miller from comment #1)
> Darren, is this even necessary with your recent signal changes?

I think it'll now work correctly anything that sets SA_RESTART but we don't do that on every platform for reasons, so this diff is probably needed for their benefit.

Comment 3 Darren Tucker 2020-05-29 15:41:03 AEST

Comment on attachment 3401 [details]
handle EINTR in connect_timeout() and waitfd()

>+		} else if (errno == EINTR)
>+			continue;

maybe also EAGAIN?

Comment 4 Damien Miller 2020-06-26 15:18:03 AEST

This has been committed and will be in OpenSSH 8.4, due in a few months - thanks

Comment 5 Darren Tucker 2020-10-02 14:55:06 AEST

Mass close of all bugs fixed in 8.4 release.