Difference in buffer behaviour between 8.89 and 8.9?

[Damien Miller]

On Wed, 6 Sep 2023, rsbecker at nexbridge.com wrote:

> On Thursday, May 19, 2022 5:21 PM, Scott Neugroschl wrote:
> >Isn't that a consequence of the limits on the nonstop READX call?
> 
> Yes it is an OS limit. I have been able to partially get this to work as
> follows:
> 
> @@ -281,6 +281,10 @@ sshbuf_read(int fd, struct sshbuf *buf, size_t maxlen,
> size_t *rlen)
> 
>         if (rlen != NULL)
>                 *rlen = 0;
> +#if defined (__TANDEM)
> +       if (maxlen > SSIZE_MAX)
> +               maxlen = SSIZE_MAX; // About 56Kb from limits.h
> +#endif
> 
> But I cannot figure out the best way to deal with the writes or the most
> acceptable way to the OpenSSH team. Any suggestions?

Is this true for all read() calls or just particular ones? If it's for
all read() calls, then maybe wrapping/replacing the read() function
more generally would be needed.

channels.c isn't the only place in OpenSSH that might do a large read...

-d