SSHD causes 100% CPU load

[Corinna Vinschen]

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.


Thanks,
Corinna