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Bug #58436 fread() fails for non-buffered streams in ssh2
Submitted: 2008-11-27 08:50 UTC Modified: 2008-12-20 12:24 UTC
From: borchinfolab at gmail dot com Assigned:
Status: Closed Package: ssh2 (PECL)
PHP Version: 5_3 CVS-2008-11-27 (dev) OS: FC9
Private report: No CVE-ID: None
 [2008-11-27 08:50 UTC] borchinfolab at gmail dot com
Description:
------------
When doing fread() from a ssh2 stream in unbuffered mode the program
core dumps.

I believe the reason for this is ether a problem with fread() or a
problem in php_ssh2_channel_stream_read(). I guess the reason for the
crash is that libssh2_channel_read_ex() in libssh2 returns -37 when the
buffer is empty -  this is handed over to fread() where I guess it
expects a positive integer.

I made a small test in php_ssh2_channel_stream_read() to see if this is
the case:

static size_t php_ssh2_channel_stream_read(php_stream *stream, char
*buf, size_t count TSRMLS_DC)
{
   php_ssh2_channel_data *abstract =
(php_ssh2_channel_data*)stream->abstract;

   stream->eof = libssh2_channel_eof(abstract->channel);
   libssh2_channel_set_blocking(abstract->channel,
abstract->is_blocking);
   int res = libssh2_channel_read_ex(abstract->channel,
abstract->streamid, buf, count);
   return(res < 0 ? 0 : res);
}

This fixed the problem for me. Perhaps the correct return value should
be EOF?

Also ssh2 does not compile for php-5.3 (this has been reported in an
other bug report) - managed to fix this by replacing statements with
correct macros.

I guess the fix will work for php-5.2.* as well, but there has been
corrections in stream_set_blocking() so it might not work after all.

This problem has been reported to php.net as well.



Reproduce code:
---------------
#!/usr/bin/php
<?php

$connection = ssh2_connect(HOSTNAME, 22, array('hostkey'=>'ssh-rsa'));
if(ssh2_auth_pubkey_file($connection, USERNAME, ID_RSA_PUB, ID_RSA, ''))
{
   $stream = ssh2_exec($connection, "ps -elf");
   // stream_set_blocking($stream, false); THIS DOSN'T WORK
   stream_set_blocking($stream, true); // THIS WORKS

   while(!feof($stream)) {
      $buf = fread($stream, 1024);
      echo ">$buf\n";
   }
}

?>


Expected result:
----------------
Output from ps -elf


Actual result:
--------------
Core dump

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History

AllCommentsChangesGit/SVN commitsRelated reports
 [2008-12-13 12:00 UTC] helgith at gmail dot com
Reassigned to proper extension
 [2008-12-20 12:24 UTC] mikesul@php.net
Thank you for your bug report. This issue has been fixed
in the latest released version of the package, which you can download at
http://pecl.php.net/get/ssh2


 
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