php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login
Bug #47540 CLI can go into an infinite write() loop when ignore_user_abort(true)
Submitted: 2009-03-02 04:01 UTC Modified: 2016-09-28 04:22 UTC
From: tstarling at wikimedia dot org Assigned: tstarling (profile)
Status: Closed Package: CGI/CLI related
PHP Version: 5.2CVS-2009-03-02 (CVS) OS: Linux
Private report: No CVE-ID: None
View Add Comment Developer Edit
Welcome! If you don't have a Git account, you can't do anything here.
You can add a comment by following this link or if you reported this bug, you can edit this bug over here.
(description)
Block user comment
Status: Assign to:
Package:
Bug Type:
Summary:
From: tstarling at wikimedia dot org
New email:
PHP Version: OS:

 

 [2009-03-02 04:01 UTC] tstarling at wikimedia dot org
Description:
------------
sapi_cli_ub_write() is faulty and may go into a tight infinite loop under certain circumstances. If write() produces an error, it calls php_handle_aborted_connection(), but if ignore_user_abort(true) has been called, this does not exit the request. Thus it enters an infinite loop.

Bug #20053 is a similar bug in a different SAPI. It's likely that many SAPIs have copied this code and suffer the same problem.

Reproduce code:
---------------
<?php
ignore_user_abort(true);
while ( true ) {
	fwrite( STDERR, microtime(true) . "\n" );
	echo "Hello\n";
	usleep(500000);
}
?>

Run it like this:

$ php nfs-test.php > /mnt/some-nfs-mount/test-file

Then while that is running, on another server:

$ rm /mnt/some-nfs-mount/test-file



Expected result:
----------------
It should exit when the file is removed, like it does when ignore_user_abort(true) is not called.

Actual result:
--------------
After a few seconds, the stderr output will stop ticking, and strace will show a flood of:

write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)
write(1, "Hello\n", 6)                  = -1 ESTALE (Stale NFS file handle)


Patches

Add a Patch

Pull Requests

Add a Pull Request

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2009-05-22 14:42 UTC] lbarnaud@php.net
Please try using this CVS snapshot:

  http://snaps.php.net/php5.2-latest.tar.gz
 
For Windows:

  http://windows.php.net/snapshots/

I believe a similar bug has been fixed in 5.2.7.
 [2009-05-30 01:00 UTC] php-bugs at lists dot php dot net
No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".
 [2016-09-28 04:22 UTC] tstarling@php.net
-Status: No Feedback +Status: Closed -Assigned To: +Assigned To: tstarling
 [2016-09-28 04:22 UTC] tstarling@php.net
I confirmed that this is fixed.
 
PHP Copyright © 2001-2021 The PHP Group
All rights reserved.
Last updated: Fri Jul 23 20:01:23 2021 UTC