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Bug #68626 A particular string and preg_replace \p{Z} causes seg fault
Submitted: 2014-12-19 03:28 UTC Modified: 2014-12-30 10:43 UTC
Avg. Score:5.0 ± 0.0
Reproduced:2 of 2 (100.0%)
Same Version:2 (100.0%)
Same OS:2 (100.0%)
From: swong at uco dot com Assigned:
Status: No Feedback Package: PCRE related
PHP Version: 5.6.4 OS: Linux
Private report: No CVE-ID: None
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 [2014-12-19 03:28 UTC] swong at uco dot com
Also tested on 
* 5.6.4 (compiled from source) on Ubuntu 14.04 x64
* 5.5.9 (from apt) on Ubuntu 14.04 x64
* 5.4.28 (from apt) on Ubuntu 10.04.4 x64
* 5.4.13 (binary) VC9 x86 on Windows

In short:
$text = "栖霞区";
$text = preg_replace('/^\p{Z}*|\p{Z}*$/u', "", $text); // Segfault and crash.
栖 in UTF-8 is "E6 A0 96"
Characters "E7 A0 96" (砖) will also repro.
Characters "E6 A1 96" (桖) does NOT repro.
Note: Unicode character U+00A0 is "non breaking space" which is in the category of \p{Z}.

Test script:
// Function 1 and Function 2 are logically the same
// Yet the preg_replace in function 1 will segfault in particular case
// Both functions is to trim spaces (of all kinds) around a string.

Function1('  TEST  ');  // prints [TEST], as expected
Function2('  TEST  ');  // prints [TEST], as expected
Function1('桖霞区');  // prints [桖霞区], as expected
Function2('桖霞区');  // prints [桖霞区], as expected
Function1('栖霞区');  // Segmentation Fault!
Function2('栖霞区');  // prints [栖霞区], as expected
Function1(' 栖霞区');  // prints [栖霞区], as expected (does not crash)
Function2(' 栖霞区');  // prints [栖霞区], as expected

function Function1($text)
    $text = preg_replace('/^\p{Z}*|\p{Z}*$/u', "", $text);
    print "[$text]\n";
function Function2($text)
    $text = preg_replace('/^\p{Z}*/u', "", $text);
    $text = preg_replace('/\p{Z}*$/u', "", $text);
    print "[$text]\n";


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 [2014-12-19 18:24 UTC]
-Status: Open +Status: Suspended
 [2014-12-19 18:24 UTC]
This appears to be a bug in PCRE itself: after compiling 8.36 (the current stable) version and linking PHP to it, I still get a segfault.

The backtrace:

#0  0x00007ffff79688be in match (eptr=0x7ffff7e55fff <error: Cannot access memory at address 0x7ffff7e55fff>, ecode=0x1090f4f "\031x", mstart=0x7ffff7ec9d71 "\240\226霞区", offset_top=2, md=0x7fffffffa6f0, eptrb=0x0, rdepth=0)
    at pcre_exec.c:5610
#1  0x00007ffff796d2af in pcre_exec (argument_re=0x1090f00, extra_data=0x7fffffffa910, subject=0x7ffff7ec9d70 "栖霞区", length=9, start_offset=1, options=8192, offsets=0x7ffff7fe1218, offsetcount=3) at pcre_exec.c:6923
#2  0x000000000047b6e8 in php_pcre_replace_impl (pce=0x1090a00, subject=0x7ffff7ec9d70 "栖霞区", subject_len=9, replace_val=0x7ffff7fe03e0, is_callable_replace=0, result_len=0x7fffffffaacc, limit=-1,
    replace_count=0x7fffffffaad0) at /home/vagrant/php-src/5.5/ext/pcre/php_pcre.c:1091
#3  0x000000000047b3c9 in php_pcre_replace (regex=0x7ffff7ec9e90 "/^\\p{Z}*|\\p{Z}*$/u", regex_len=18, subject=0x7ffff7ec9d70 "栖霞区", subject_len=9, replace_val=0x7ffff7fe03e0, is_callable_replace=0,
    result_len=0x7fffffffaacc, limit=-1, replace_count=0x7fffffffaad0) at /home/vagrant/php-src/5.5/ext/pcre/php_pcre.c:997
#4  0x000000000047c627 in php_replace_in_subject (regex=0x7ffff7fe02f0, replace=0x7ffff7fe03e0, subject=0x7ffff7fa83d8, result_len=0x7fffffffaacc, limit=-1, is_callable_replace=0, replace_count=0x7fffffffaad0)
    at /home/vagrant/php-src/5.5/ext/pcre/php_pcre.c:1318
#5  0x000000000047d098 in preg_replace_impl (ht=3, return_value=0x7ffff7fe0368, return_value_ptr=0x0, this_ptr=0x0, return_value_used=1, is_callable_replace=0, is_filter=0) at /home/vagrant/php-src/5.5/ext/pcre/php_pcre.c:1416
#6  0x000000000047d1b6 in zif_preg_replace (ht=3, return_value=0x7ffff7fe0368, return_value_ptr=0x0, this_ptr=0x0, return_value_used=1) at /home/vagrant/php-src/5.5/ext/pcre/php_pcre.c:1436
#7  0x000000000082179a in zend_do_fcall_common_helper_SPEC (execute_data=0x7ffff7fa8318) at /home/vagrant/php-src/5.5/Zend/zend_vm_execute.h:550
#8  0x00000000008260cd in ZEND_DO_FCALL_SPEC_CONST_HANDLER (execute_data=0x7ffff7fa8318) at /home/vagrant/php-src/5.5/Zend/zend_vm_execute.h:2332
#9  0x0000000000820e8d in execute_ex (execute_data=0x7ffff7fa8318) at /home/vagrant/php-src/5.5/Zend/zend_vm_execute.h:363
#10 0x0000000000820f16 in zend_execute (op_array=0x7ffff7fdde48) at /home/vagrant/php-src/5.5/Zend/zend_vm_execute.h:388
#11 0x00000000007e202d in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/vagrant/php-src/5.5/Zend/zend.c:1327
#12 0x000000000074b10c in php_execute_script (primary_file=0x7fffffffd1f0) at /home/vagrant/php-src/5.5/main/main.c:2506
#13 0x0000000000890c8b in do_cli (argc=2, argv=0xf15a50) at /home/vagrant/php-src/5.5/sapi/cli/php_cli.c:994
#14 0x0000000000891fb9 in main (argc=2, argv=0xf15a50) at /home/vagrant/php-src/5.5/sapi/cli/php_cli.c:1378

This needs to be reported to PCRE at
 [2014-12-20 10:05 UTC]
-Status: Suspended +Status: Feedback
 [2014-12-20 10:05 UTC]
Hm, to my experience this passes on master which is using 8.35. But yeah, PHP5 it's a crash, no matter which pcre.

>	php5ts_debug.dll!match(const unsigned char * eptr, const unsigned char * ecode, const unsigned char * mstart, int offset_top, match_data * md, eptrblock * eptrb, unsigned int rdepth) Line 5593	C
 	php5ts_debug.dll!php_pcre_exec(const real_pcre * argument_re, const pcre_extra * extra_data, const char * subject, int length, int start_offset, int options, int * offsets, int offsetcount) Line 6945	C
 	php5ts_debug.dll!php_pcre_replace_impl(pcre_cache_entry * pce, char * subject, int subject_len, _zval_struct * replace_val, int is_callable_replace, int * result_len, int limit, int * replace_count, void * * * tsrm_ls) Line 1093	C
 	php5ts_debug.dll!php_pcre_replace(char * regex, int regex_len, char * subject, int subject_len, _zval_struct * replace_val, int is_callable_replace, int * result_len, int limit, int * replace_count, void * * * tsrm_ls) Line 999	C
 	php5ts_debug.dll!php_replace_in_subject(_zval_struct * regex, _zval_struct * replace, _zval_struct * * subject, int * result_len, int limit, int is_callable_replace, int * replace_count, void * * * tsrm_ls) Line 1327	C
 	php5ts_debug.dll!preg_replace_impl(int ht, _zval_struct * return_value, _zval_struct * * return_value_ptr, _zval_struct * this_ptr, int return_value_used, void * * * tsrm_ls, int is_callable_replace, int is_filter) Line 1417	C
 	php5ts_debug.dll!zif_preg_replace(int ht, _zval_struct * return_value, _zval_struct * * return_value_ptr, _zval_struct * this_ptr, int return_value_used, void * * * tsrm_ls) Line 1438	C
 	php5ts_debug.dll!zend_do_fcall_common_helper_SPEC(_zend_execute_data * execute_data, void * * * tsrm_ls) Line 551	C
 	php5ts_debug.dll!ZEND_DO_FCALL_SPEC_CONST_HANDLER(_zend_execute_data * execute_data, void * * * tsrm_ls) Line 2333	C
 	php5ts_debug.dll!execute_ex(_zend_execute_data * execute_data, void * * * tsrm_ls) Line 363	C
 	php5ts_debug.dll!zend_execute(_zend_op_array * op_array, void * * * tsrm_ls) Line 389	C
 	php5ts_debug.dll!zend_execute_scripts(int type, void * * * tsrm_ls, _zval_struct * * retval, int file_count, ...) Line 1328	C
 	php5ts_debug.dll!php_execute_script(_zend_file_handle * primary_file, void * * * tsrm_ls) Line 2506	C
 	php.exe!do_cli(int argc, char * * argv, void * * * tsrm_ls) Line 995	C
 	php.exe!main(int argc, char * * argv) Line 1378	C
 	php.exe!__tmainCRTStartup() Line 536	C
 	php.exe!mainCRTStartup() Line 377	C

@swong at uco dot com, I'd like to ask you to check master yet. Unfortunately I can't say whether it operates correctly as I don't read hieroglyphs. So despite it doesn't crash there, one can be 100% sure it's correct.

 [2014-12-30 10:43 UTC] php-bugs at lists dot php dot net
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