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Bug #38600 libpcre needs update to 6.7: Infinite loop using preg_match
Submitted: 2006-08-25 21:14 UTC Modified: 2006-08-30 20:08 UTC
Avg. Score:5.0 ± 0.0
Reproduced:2 of 2 (100.0%)
Same Version:1 (50.0%)
Same OS:2 (100.0%)
From: phillip dot berndt at googlemail dot com Assigned: andrei (profile)
Status: Closed Package: PCRE related
PHP Version: 5.1.5 OS: Linux
Private report: No CVE-ID: None
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 [2006-08-25 21:14 UTC] phillip dot berndt at googlemail dot com
When executing the code below, the function won't return but loop forever (or do something else, I don't know).

Reproduce code:
        $foo = 'bla bla bla';
        preg_match('/(?<!\w)(0x[\p{N}]+[lL]?|[\p{Nd}]+(e[\p{Nd}]*)?[lLdDfF]?)(?!\w)/', $foo);

Expected result:
Something like that:

pberndt@locutus ~ $ time perl -e '$_="bla bla bla"; /(?<!\w)(0x[\p{N}]+[lL]?|[\p{Nd}]+(e[\p{Nd}]*)?[lLdDfF]?)(?!\w)/;'

real    0m0.017s
user    0m0.016s
sys     0m0.000s

Actual result:
pberndt@locutus ~ $ php
        $foo = 'bla bla bla';
        preg_match('/(?<!\w)(0x[\p{N}]+[lL]?|[\p{Nd}]+(e[\p{Nd}]*)?[lLdDfF]?)(?!\w)/', $foo);

Fatal error: Maximum execution time of 10 seconds exceeded in /home/pberndt/- on line 4


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 [2006-08-25 21:39 UTC]
Please try using this CVS snapshot:
For Windows:

 [2006-08-26 13:40 UTC] phillip dot berndt at googlemail dot com
Same result for a fresh php5.2-200608261230 build.

I don't know, whether this helps, but in this build I interrupted the process after about 10 seconds; here's the bt:

#0  adjust_recurse (group=0x84706db "R", adjust=1, utf8=0, cd=0xbfd088e0) at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/pcrelib/pcre_compile.c:1117
#1  0x08080269 in compile_regex (options=0, oldims=0, brackets=0xbfd084a4, codeptr=0xbfd08344, ptrptr=0xbfd0837c, errorcodeptr=0xbfd084dc, lookbehind=0,
    skipbytes=0, firstbyteptr=0x0, reqbyteptr=0x0, bcptr=0x3d, cd=0xbfd088e0) at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/pcrelib/pcre_compile.c:2681
#2  0x0807e71a in compile_regex (options=0, oldims=0, brackets=0xbfd084a4, codeptr=0xbfd084a8, ptrptr=0xbfd084d8, errorcodeptr=0xbfd084dc, lookbehind=0,
    skipbytes=0, firstbyteptr=0x0, reqbyteptr=0x0, bcptr=0x3d, cd=0xbfd088e0) at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/pcrelib/pcre_compile.c:3177
#3  0x08081339 in php_pcre_compile2 (pattern=0xb7bdf6d8 "(?<!\\w)(0x[\\p{N}]+[lL]?|[\\p{Nd}]+(e[\\p{Nd}]*)?[lLdDfF]?)(?!\\w)", options=0, errorcodeptr=0x0,
    errorptr=0xbfd089a4, erroroffset=0xbfd089a8, tables=0x8470220 "") at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/pcrelib/pcre_compile.c:4983
#4  0x080829a3 in php_pcre_compile (pattern=0x0, options=0, errorptr=0x0, erroroffset=0x0, tables=0x0)
    at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/pcrelib/pcre_compile.c:3905
#5  0x0808bfad in pcre_get_compiled_regex_cache (regex=0xb7be4bd4 "/(?<!\\w)(0x[\\p{N}]+[lL]?|[\\p{Nd}]+(e[\\p{Nd}]*)?[lLdDfF]?)(?!\\w)/", regex_len=64)
    at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/php_pcre.c:324
#6  0x0808d225 in php_do_pcre_match (ht=2, return_value=0xb7be4c20, return_value_ptr=0x0, this_ptr=0x0, return_value_used=0, global=0)
    at /home/pberndt/php_snap/php5.2-200608261230/ext/pcre/php_pcre.c:457
#7  0x082292d7 in zend_do_fcall_common_helper_SPEC (execute_data=0xbfd08b60) at zend_vm_execute.h:200
#8  0x08228bdc in execute (op_array=0xb7be47d8) at zend_vm_execute.h:92
#9  0x0820dabe in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/pberndt/php_snap/php5.2-200608261230/Zend/zend.c:1095
#10 0x081cfb86 in php_execute_script (primary_file=0xbfd0b060) at /home/pberndt/php_snap/php5.2-200608261230/main/main.c:1759
#11 0x082963b0 in main (argc=1, argv=0xbfd0b144) at /home/pberndt/php_snap/php5.2-200608261230/sapi/cli/php_cli.c:1102
 [2006-08-26 14:55 UTC] phillip dot berndt at googlemail dot com
This should be the problem:

ChangeLog for PCRE
Version 6.7 04-Jul-06
 4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
    containing an extended class (one that cannot be represented by a bitmap
    because it contains high-valued characters or Unicode property items, e.g.
    [\pZ]). Almost always one would set UTF-8 mode when processing such a
    pattern, but PCRE should not loop if you do not (it no longer does).
    [Detail: two cases were found: (a) a repeated subpattern containing an
    extended class; (b) a recursive reference to a subpattern that followed a
    previous extended class. It wasn't skipping over the extended class
    correctly when UTF-8 mode was not set.]
 [2006-08-26 22:33 UTC] phillip dot berndt at googlemail dot com
Changed title to fit better. Sorry for posting another comment, I can't submit the update without posting something :)

I just tested updating the php source to use the newest libpcre - everything is working perfectly.
 [2006-08-30 20:08 UTC]
This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
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