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Request #48506 upcoming apr closes descriptors by default
Submitted: 2009-06-09 13:47 UTC Modified: 2020-11-15 04:22 UTC
From: arekm at maven dot pl Assigned: cmb (profile)
Status: No Feedback Package: Apache2 related
PHP Version: 5.2.9 OS:
Private report: No CVE-ID: None
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 [2009-06-09 13:47 UTC] arekm at maven dot pl
Description:
------------
Upcoming apr 2.0.0 (or 1.3 with backported patch) uses O_CLOEXEC for own descriptors by default.

This means that when using shell_exec() the run script/binary has no stdin/stdout/stderr due to O_CLOEXEC. This also means that if any output is produced then script ends with EPIPE.

Tested with apache + apr 1.3 with backported patch.

http://svn.apache.org/viewvc/apr/apr/trunk/CHANGES?r1=747357&r2=748988



Reproduce code:
---------------
<?php
echo shell_exec("LC_ALL=C strace -o /tmp/WYNIK -f -F -s 200 ls -l /notexistingfile");
?>

Run from apache + php + apr 1.3 + backported O_CLOEXEC patch like this one http://cvs.pld-linux.org/cgi-bin/cvsweb/packages/apr/apr-bug-46425.patch?rev=1.8

Expected result:
----------------
run "ls -l" and produce some output about file not existing

Actual result:
--------------
30120 lstat("/notexistingfile", 0x18f55f0) = -1 ENOENT (No such file or directory)
30120 write(2, "ls: ", 4)               = -1 EBADF (Bad file descriptor)
30120 write(2, "cannot access /notexistingfile", 30) = -1 EBADF (Bad file descriptor)
30120 write(2, ": No such file or directory", 27) = -1 EBADF (Bad file descriptor)
30120 write(2, "\n", 1)                 = -1 EBADF (Bad file descriptor)
30120 close(1)                          = 0
30120 close(2)                          = -1 EBADF (Bad file descriptor)
30120 exit_group(2)

As you can see there is no file descriptor 2 and this means that ls output is lost.


Probably the best for php is to always provide own descriptors without relying on apache provided one.           

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History

AllCommentsChangesGit/SVN commitsRelated reports
 [2009-07-25 15:01 UTC] arekm at maven dot pl
Note that latest released stable apr 1.3.6 also contains these changes and distributions will start to pick up these soon.)
 [2010-12-20 14:28 UTC] jani@php.net
-Package: Feature/Change Request +Package: Apache2 related
 [2017-10-24 06:12 UTC] kalle@php.net
-Status: Assigned +Status: Open -Assigned To: scottmac +Assigned To:
 [2020-11-05 13:49 UTC] cmb@php.net
-Status: Open +Status: Feedback -Assigned To: +Assigned To: cmb
 [2020-11-05 13:49 UTC] cmb@php.net
I assume that this has already been catered to, hasn't it?
 [2020-11-15 04:22 UTC] php-bugs at lists dot php dot net
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Re-Opened". Thank you.
 
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