Re: SSHD causes 100% CPU load

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

On Aug  6 20:14, Takashi Yano via Cygwin wrote:
> On Fri, 6 Aug 2021 11:11:05 +0200
> Corinna Vinschen wrote:
> > On Aug  6 10:55, Takashi Yano via Cygwin wrote:
> > > Hi Corinna,
> > > 
> > > On Fri, 6 Aug 2021 01:43:31 +0900
> > > Takashi Yano wrote:
> > > > Hi Corinna,
> > > > 
> > > > On Thu, 5 Aug 2021 17:07:24 +0200
> > > > Corinna Vinschen wrote:
> > > > > Could you perhaps bisect the issue on your machine?
> > > > 
> > > > In my environment, this does not happen with 8.4p1-1 and 8.4p1-2.
> > > > However it happens with 8.5p1-1.
> > > > [...]
> > > I looked into the openssh code and might find a calprit.
> > > I guess the following patch solves the issue.
> > > 
> > > --- serverloop.c.orig	2021-03-02 19:31:47.000000000 +0900
> > > +++ serverloop.c	2021-08-06 10:41:55.439357200 +0900
> > > @@ -333,7 +333,7 @@
> > >  			return -1;
> > >  		} else if (len == -1) {
> > >  			if (errno == EINTR || errno == EAGAIN ||
> > > -			    errno != EWOULDBLOCK)
> > > +			    errno == EWOULDBLOCK)
> > >  				return 0;
> > >  			verbose("Read error from remote host %s port %d: %s",
> > >  			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
> > > 
> > > 
> > > This seems to be a upstream bug which has been already fixed.
> > > 
> > > Please refer to:
> > > https://github.com/openssh/openssh-portable/commit/2dc328023f60212cd29504fc05d849133ae47355
> > 
> > Gosh, looks like I totally missed the 8.6p1 release!
> > 
> > I'll build and upload 8.6p1 ASAP.
> 
> I have confirmed that the issue has been fixed in 8.6p1-1.

Great, thanks for testing!


Corinna