From:  pear-qa@lists.php.net ("mmn@hethane.se")
Date:  11 Jul 2017 18:23:07 Hong Kong Time
Newsgroup:  news.php.net/php.pear.bugs
Subject:  

[PEAR-BUG] Bug #21229 [Com]: fgets never times out with malicious server

NNTP-Posting-Host:  null

Edit report at https://pear.php.net/bugs/bug.php?id=21229&edit=1

 ID:               21229
 Comment by:       mmn at hethane dot se
 Reported By:      mmn at hethane dot se
 Summary:          fgets never times out with malicious server
 Status:           Open
 Type:             Bug
 Package:          HTTP_Request2
 Operating System: Debian
 Package Version:  2.3.0
 PHP Version:      Irrelevant
 Roadmap Versions: 
 New Comment:

I think the stream_select solution I have added as a patch here should
work well as a solution too. It'll force fgets to stick within the given
time parameter (unless both localTimeout and deadline is null, then null
is given which is infinite time).

I think I've formatted the patch properly for v2.3.0, let me know
otherwise.

I've patched this in the bundled library for GNU social, where I
experienced this issue, here:
https://git.gnu.io/gnu/gnu-social/commit/05a9c11c476b384e5ef3f3cc83b66406fcf7a378


Previous Comments:
------------------------------------------------------------------------

[2017-07-11 06:19:50] mmn

Added #patch
bug:21229;patch:stream_select_for_fgets;revision:1499768390;.

------------------------------------------------------------------------

[2017-07-10 16:13:34] mmn

Description:
------------
The usage of 'fgets' in HTTP_Request2_SocketWrapper -> readLine makes it
possible for remote servers to reply r-e-a-l-l-y s-l-o-w-l-y and thus
blocking a PHP process.

It seems that 'fread' will time out properly, while 'fgets' does not:
https://secure.php.net/fgets vs. https://secure.php.net/fread

In practice, fread seems to appropriately time out when reading from an
extremely slow stream, while fgets simply continues until it reaches
bufferSize (default 16Ki) or a newline (a malicious server can choose to
never send a newline, causing a script to time out only after 16000
seconds because of the buffer size having to be filled up).

It seems to fix this, we should have a small internal buffer and make
sure to use 'fread' instead of 'fgets' but simulate the stop-at-newline
functionality as it's often used to read in HTTP headers etc.

A thread related to this in GNU social's use of HTTP_Request2 can be
found here: https://git.gnu.io/gnu/gnu-social/issues/281#note_5674

------------------------------------------------------------------------


-- 
Edit this bug report at https://pear.php.net/bugs/bug.php?id=21229&edit=1