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[2014-10-17 14:07 UTC] bugs at milos dot nz
Description:
------------
WordPress sites with certain plugins enabled cause a segmentation fault. Several different sites with different plugins cause this and the segmentation fault is the same. I have not encountered the issue with any isolated PHP script so I cannot currently be more specific than this.
Commenting out most of the _zend_hash_del_el() function resolves the issue, however this must either reduce performance, cause memory leaks or other anomalies, so if anything this is a temporary workaround:
static zend_always_inline void _zend_hash_del_el(HashTable *ht, uint32_t idx, Bucket *p)
{
Bucket *prev = NULL;
/*if (!(ht->u.flags & HASH_FLAG_PACKED)) {
uint32_t nIndex = p->h & ht->nTableMask;
uint32_t i = ht->arHash[nIndex];
if (i != idx) {
prev = ht->arData + i;
while (Z_NEXT(prev->val) != idx) {
i = Z_NEXT(prev->val);
prev = ht->arData + i;
}
}
}*/
_zend_hash_del_el_ex(ht, idx, p, prev);
}
Test script:
---------------
I am not able to identify exactly what code causes the segmentation fault so cannot provide a test script at this current point in time, but the segmentation fault is 100% reproducible on my system.
Expected result:
----------------
No segmentation fault.
Actual result:
--------------
Program received signal SIGSEGV, Segmentation fault.
_zend_hash_del_el (p=0x7fffeff117b0, idx=1725, ht=0xf81890) at /root/tmp/php-src/Zend/zend_hash.c:658
658 while (Z_NEXT(prev->val) != idx) {
(gdb) bt
#0 _zend_hash_del_el (p=0x7fffeff117b0, idx=1725, ht=0xf81890) at /root/tmp/php-src/Zend/zend_hash.c:658
#1 zend_hash_apply_deleter (ht=ht@entry=0xf81890, idx=idx@entry=1725, p=p@entry=0x7fffeff117b0) at /root/tmp/php-src/Zend/zend_hash.c:973
#2 0x000000000074b0a9 in zend_hash_reverse_apply (ht=0xf81890, apply_func=apply_func@entry=0x729ee0 <clean_non_persistent_function>) at /root/tmp/php-src/Zend/zend_hash.c:1133
#3 0x000000000072a6b8 in shutdown_executor () at /root/tmp/php-src/Zend/zend_execute_API.c:347
#4 0x000000000073ac17 in zend_deactivate () at /root/tmp/php-src/Zend/zend.c:883
#5 0x00000000006dface in php_request_shutdown (dummy=dummy@entry=0x0) at /root/tmp/php-src/main/main.c:1859
#6 0x0000000000484214 in main (argc=2, argv=0x7fffffffe078) at /root/tmp/php-src/sapi/cgi/cgi_main.c:2515
(gdb) print prev
$1 = (Bucket *) 0x801feff03ff0
(gdb) print prev->val
Cannot access memory at address 0x801feff04000
(gdb) print idx
$2 = 1725
The issue is apparently here:
658: while (Z_NEXT(prev->val) != idx) {
However, I am not sure if the fault lies in _zend_hash_del_el() itself or if _zend_hash_del_el() is being called with incorrect arguments.
An identical segmentation fault occurs when calling this WordPress index.php script through apache2 with PHP as a SAPI module.
The master PHP branch was compiled with the following options:
'./configure' '--prefix=/root/tmp/usr' '--build=x86_64-pc-linux-gnu' '--host=x86_64-pc-linux-gnu' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--datadir=/usr/share' '--sysconfdir=/etc' '--localstatedir=/var/lib' '--prefix=/usr/lib64/php7.0' '--mandir=/usr/lib64/php7.0/man' '--infodir=/usr/lib64/php7.0/info' '--libdir=/usr/lib64/php7.0/lib' '--with-libdir=lib64' '--without-pear' '--disable-maintainer-zts' '--enable-bcmath' '--with-bz2=/usr' '--enable-calendar' '--enable-ctype' '--with-curl=/usr' '--enable-dom' '--without-enchant' '--disable-exif' '--enable-fileinfo' '--enable-filter' '--disable-ftp' '--with-gettext=/usr' '--without-gmp' '--enable-hash' '--with-mhash=/usr' '--with-iconv' '--enable-intl' '--enable-ipv6' '--enable-json' '--without-kerberos' '--enable-libxml' '--with-libxml-dir=/usr' '--enable-mbstring' '--with-mcrypt=/usr' '--without-mssql' '--with-onig=/usr' '--with-openssl=/usr' '--with-openssl-dir=/usr' '--disable-pcntl' '--enable-phar' '--enable-pdo' '--enable-opcache' '--without-pgsql' '--enable-posix' '--with-pspell=/usr' '--without-recode' '--enable-simplexml' '--disable-shmop' '--without-snmp' '--disable-soap' '--enable-sockets' '--without-sqlite3' '--without-sybase-ct' '--disable-sysvmsg' '--disable-sysvsem' '--disable-sysvshm' '--without-fpm-systemd' '--without-tidy' '--enable-tokenizer' '--disable-wddx' '--enable-xml' '--enable-xmlreader' '--enable-xmlwriter' '--without-xmlrpc' '--without-xsl' '--enable-zip' '--with-zlib=/usr' '--disable-debug' '--enable-dba' '--without-cdb' '--with-db4=/usr' '--disable-flatfile' '--with-gdbm=/usr' '--disable-inifile' '--without-qdbm' '--with-freetype-dir=/usr' '--with-t1lib=/usr' '--disable-gd-jis-conv' '--with-jpeg-dir=/usr' '--with-png-dir=/usr' '--without-xpm-dir' '--without-vpx-dir' '--with-gd' '--with-imap=/usr' '--with-imap-ssl=/usr' '--with-mysql=/usr' '--with-mysqli=/usr/bin/mysql_config' '--with-mysql-sock=/var/run/mysqld/mysqld.sock' '--without-pdo-dblib' '--with-pdo-mysql=/usr' '--without-pdo-pgsql' '--without-pdo-sqlite' '--without-pdo-odbc' '--with-readline=/usr' '--without-libedit' '--without-mm' '--with-pic' '--with-pcre-regex=/usr' '--with-pcre-dir=/usr' '--with-config-file-path=/root/tmp/usr/etc' '--disable-embed' '--enable-cli' '--enable-cgi' '--enable-fpm' '--with-apxs2=/usr/sbin/apxs2' 'build_alias=x86_64-pc-linux-gnu' 'host_alias=x86_64-pc-linux-gnu'
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Last updated: Thu Oct 30 21:00:01 2025 UTC |
"i" is optimised out and I see no mention of "arData". I will try and recompile with -O0 when I find the appropriate setting in the Makefile and then I'll post my findings here. In the meantime, this is the output of `bt full` (with -O2, I *think*) in gdb: (gdb) bt full #0 _zend_hash_del_el (p=0x7fffeff117b0, idx=1725, ht=0xf7f880) at /root/tmp/php-src/Zend/zend_hash.c:658 nIndex = 643 i = <optimized out> prev = 0x801feff03ff0 #1 zend_hash_apply_deleter (ht=ht@entry=0xf7f880, idx=idx@entry=1725, p=p@entry=0x7fffeff117b0) at /root/tmp/php-src/Zend/zend_hash.c:973 No locals. #2 0x000000000074a219 in zend_hash_reverse_apply (ht=0xf7f880, apply_func=apply_func@entry=0x729210 <clean_non_persistent_function>) at /root/tmp/php-src/Zend/zend_hash.c:1133 idx = 1725 p = 0x7fffeff117b0 result = 1 #3 0x00000000007299e8 in shutdown_executor () at /root/tmp/php-src/Zend/zend_execute_API.c:347 __orig_bailout = 0x7fffffffddc0 __bailout = {{__jmpbuf = {163, -5169695161297403702, 140737488347264, 1, 17475568, 54, 5169695577156354250, -5169695152520429366}, __mask_was_saved = 0, __saved_mask = {__val = {13277048765369942218, 4294967296, 13277048817496228042, 0, 16230304, 16217536, 5950268, 0, 16605696, 140737228258144, 1, 16230768, 16232032, 1, 7569822, 16231936}}}} func = <optimized out> ce = <optimized out> #4 0x0000000000739da7 in zend_deactivate () at /root/tmp/php-src/Zend/zend.c:883 No locals. #5 0x00000000006dedfe in php_request_shutdown (dummy=dummy@entry=0x0) at /root/tmp/php-src/main/main.c:1859 report_memleaks = 1 '\001' #6 0x0000000000483514 in main (argc=2, argv=0x7fffffffe078) at /root/tmp/php-src/sapi/cgi/cgi_main.c:2515 __orig_bailout = 0x0 __bailout = {{__jmpbuf = {0, -5169695578150403894, 4737515, 140737488347248, 0, 0, 5169695577051496650, -5169694958687092534}, __mask_was_saved = 0, __saved_mask = {__val = {140737488346912, 46, 140737354015960, 0, 140737353971216, 140737353975024, 4472388, 140737229643112, 4276008, 4294967296, 4294969391, 140737229617936, 140737353971216, 140737488347072, 140737354130592, 140737488347112}}}} free_query_string = 1 exit_status = 0 cgi = 0 c = <optimized out> i = <optimized out> len = <optimized out> file_handle = {handle = {fd = -261734144, fp = 0x7ffff0664100, stream = {handle = 0x7ffff0664100, isatty = 0, mmap = {len = 418, pos = 0, map = 0x0, buf = 0x7ffff7ff6000 "", old_handle = 0x0, old_closer = 0x0}, reader = 0x6f6360 <_php_stream_read>, fsizer = 0x6dc7b0 <php_zend_stream_fsizer>, closer = 0x6dc790 <php_zend_stream_mmap_closer>}}, filename = 0x7ffff0602000 " \rh\360\377\177", opened_path = 0x0, type = ZEND_HANDLE_MAPPED, free_filename = 0 '\000'} s = <optimized out> behavior = 1 no_headers = <optimized out> orig_optind = 1 orig_optarg = 0x0 script_file = <optimized out> ini_entries_len = <optimized out> max_requests = 500 requests = 0 fastcgi = 0 bindpath = <optimized out> fcgi_fd = <optimized out> request = 0x0 warmup_repeats = 0 repeats = 1 benchmark = <optimized out> start = {tv_sec = 140733193388093, tv_usec = 140737314330200} end = {tv_sec = 1, tv_usec = 140737351931677} status = 0 query_string = <optimized out> decoded_query_string = <optimized out> skip_getopt = <optimized out>The latest master PHP branch recompiled sans optimisation (-O0) results in the following gdb backtrace: (gdb) bt full #0 0x0000000000974b73 in _zend_hash_del_el (p=0x7fffeff117b0, idx=1725, ht=0x129c880) at /root/tmp/php-src/Zend/zend_hash.c:658 nIndex = 643 i = 4294967295 prev = 0x801feff03ff0 #1 zend_hash_apply_deleter (ht=0x129c880, idx=1725, p=0x7fffeff117b0) at /root/tmp/php-src/Zend/zend_hash.c:973 No locals. #2 0x00000000009753c7 in zend_hash_reverse_apply (ht=0x129c880, apply_func=0x93313a <clean_non_persistent_function>) at /root/tmp/php-src/Zend/zend_hash.c:1133 idx = 1725 p = 0x7fffeff117b0 result = 1 #3 0x0000000000933da1 in shutdown_executor () at /root/tmp/php-src/Zend/zend_execute_API.c:347 __orig_bailout = 0x7fffffffddf0 __bailout = {{__jmpbuf = {0, -8375293845698859549, 4721632, 140737488347248, 0, 0, -8375293845684179485, 8375292634278702563}, __mask_was_saved = 0, __saved_mask = {__val = {140737226576512, 9343290, 19498944, 140737488345520, 18446744073447799296, 140737488345520, 9772479, 0, 139646304518208, 9343290, 19498944, 140737226211328, 19498944, 140737488345552, 9343543, 140737226604240}}}} func = 0x129c830 ce = 0x176eee0 #4 0x0000000000954b71 in zend_deactivate () at /root/tmp/php-src/Zend/zend.c:883 No locals. #5 0x00000000008ab3d6 in php_request_shutdown (dummy=0x0) at /root/tmp/php-src/main/main.c:1859 report_memleaks = 1 '\001' #6 0x0000000000ad5df5 in main (argc=2, argv=0x7fffffffe078) at /root/tmp/php-src/sapi/cgi/cgi_main.c:2515 __orig_bailout = 0x0 __bailout = {{__jmpbuf = {0, -8375293845908574749, 4721632, 140737488347248, 0, 0, -8375293845814202909, 8375292580019351011}, __mask_was_saved = 0, __saved_mask = {__val = {4478074, 140737229643112, 4277064, 4294967296, 4294969391, 140737229617936, 140737353971192, 140737488347072, 140737354130592, 140737488347112, 140737354129736, 1, 140737351931677, 0, 140737353971192, 1}}}} free_query_string = 1 exit_status = 0 cgi = 0 c = -1 i = 2 len = 54 file_handle = {handle = {fd = -261734144, fp = 0x7ffff0664100, stream = {handle = 0x7ffff0664100, isatty = 0, mmap = {len = 418, pos = 0, map = 0x0, buf = 0x7ffff7ff6000 "", old_handle = 0x0, old_closer = 0x0}, reader = 0x8cb19a <_php_stream_read>, fsizer = 0x8aa26b <php_zend_stream_fsizer>, closer = 0x8aa245 <php_zend_stream_mmap_closer>}}, filename = 0x7ffff0602000 " \rh\360\377\177", opened_path = 0x0, type = ZEND_HANDLE_MAPPED, free_filename = 0 '\000'} s = 0x13c77f0 "/home/simon/theibguide.com/www/public_html/index.php" behavior = 1 no_headers = 0 orig_optind = 1 orig_optarg = 0x0 script_file = 0x0 ini_entries_len = 0 max_requests = 500 requests = 0 fastcgi = 0 bindpath = 0x0 fcgi_fd = 0 request = 0x0 warmup_repeats = 0 repeats = 1 benchmark = 0 start = {tv_sec = 140737229643112, tv_usec = 140737314262832} end = {tv_sec = 1, tv_usec = 140737354129736} status = 0 query_string = 0x0 decoded_query_string = 0x7ffff7de5594 <do_lookup_x+2324> "H\205\300L\213L$\030L\213\\$(D\213D$0\017\205\216\370\377\377H\213T$\020\213\n\353\203ff.\017\037\204" skip_getopt = 0thanks for your help, I have made a reproduce script <?php function a() { } create_function('', 'var_dump("22");'); a(); I will fix it soon