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Bug #40414 endless fork() loop when running fastcgi
Submitted: 2007-02-09 10:09 UTC Modified: 2007-02-15 12:34 UTC
From: michiel at boland dot org Assigned: dmitry
Status: Closed Package: CGI/CLI related
PHP Version: 5.2.0 OS: Solaris
Private report: No CVE-ID:
 [2007-02-09 10:09 UTC] michiel at boland dot org
Description:
------------
PHP running as fastcgi under apache2, with
PHP_FCGI_CHILDREN set to 2.

Under certain circumstances, the parent PHP process
keeps forking off child processes that exit immediately.
This goes on forever, until the parent is killed.

When I run a debugger, the in_shutdown variable (in
sapi/cgi/fastcgi.c) is set to 1. This causes
fcgi_accept_request, which is called in child
processes, to return immediately.

The only place where in_shutdown can be set is in the
SIGTERM signal handler, fcgi_signal_handler.

The fcgi_signal_handler is installed in fcgi_init, which
is called via fcgi_is_fastcgi, right after entry into
main().

Later on in cgi_main.c, a new SIGTERM handler is installed.
(line 1334)

If a SIGTERM signal arrives in the window of time between
fcgi_init and the setting of the new signal handler, the
loop describe above will occur.

As a fix I would suggest blocking SIGTERM in main()
until after the new handler is in place.


Reproduce code:
---------------
n/a


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 [2007-02-15 12:34 UTC] dmitry@php.net
Fixed in CVS HEAD and PHP_5_2.
 
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