Bug #53099 [Asn->Nab]: mb_ereg_replace uses 100% cpu and takes >10 minutes to execute.

Edit report at https://bugs.php.net/bug.php?id=53099&edit=1 ID: 53099 Updated by: cmb@php.net Reported by: phpnet at rcpt dot at Summary: mb_ereg_replace uses 100% cpu and takes >10 minutes to execute. -Status: Assigned +Status: Not a bug Type: Bug Package: mbstring related Operating System: Ubuntu 9.10 PHP Version: 5.3.3 -Assigned To: moriyoshi +Assigned To: cmb Block user comment: N Private report: N New Comment: > The second pattern in your function is problematic: > (\s|\t|\n\r)*$ Indeed. Request #72777 appears to be helpful in this regard. Previous Comments: ------------------------------------------------------------------------ [2016-07-30 13:06:31] ju1ius at laposte dot net This is not a bug, this is catastrophic backtracking. http://www.regular-expressions.info/catastrophic.html The second pattern in your function is problematic: (\s|\t|\n\r)*$ All regexps engines will choke on that. ------------------------------------------------------------------------ [2016-07-30 11:34:00] cmb@php.net Related To: Bug #60664 ------------------------------------------------------------------------ [2010-10-19 12:52:43] phpnet at rcpt dot at Thanks felipe, sorry about that; to avoid confusion, I mean 'mb_ereg_replace' not 'ereg_replace'. ------------------------------------------------------------------------ [2010-10-18 22:32:40] felipe@php.net s/ereg_replace/mb_ereg_replace/g :) ------------------------------------------------------------------------ [2010-10-18 17:28:09] phpnet at rcpt dot at Description: ------------ I have written a mb_trim function in php which uses ereg_replace to trim strings in the same manner as trim() does. The function is available at http://php.net/manual/en/ref.mbstring.php Under the heading 'phpnet at rcpt dot at - 19-Aug-2010 02:46' Using the string excerpt from our production environment (http://pastebin.com/wmyjPmBV), ereg_replace appears to enter some sort of recursive loop, in my environment it takes 100% cpu for 20 minutes before finally returning the correct result. When the section which reads: array( "\s","\t","\n","\r", "\0", "\x0B" ) ...is changed to array( "\s", "\0", "\x0B" ) then ereg_replace returns promptly with the correct result. Test script: --------------- The function is available at http://php.net/manual/en/ref.mbstring.php Under the heading 'phpnet at rcpt dot at - 19-Aug-2010 02:46' It is also available here: http://pastebin.com/CCpaVXay The (serialized) string that causes the problem is: s:488:"<I>Swans </I> Wisely moving from the middle of July to the middle of autumn, this indoor, forward-thinking avant-rock weekend brings together all sorts of fiercely experimental noisemakers, from psychedelic-folk to death metal, with a hotly anticipated headline set from Michael Gira's New York noise inspiration Swans. Don't expect many stony-faced rock nerds, though. The organisers serve tea and cake throughout and they're promising other fun and games this year."; It is also available for download here: http://pastebin.com/wmyjPmBV You can execute the script with the following syntax: <?php mb_trim( $string ); Expected result: ---------------- PHP will return the correct result quickly. Actual result: -------------- PHP will run at 100% CPU for 20 minutes. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=53099&edit=1