Bug #68252 [Com]: segfault in Zend/zend_hash.c in function _zend_hash_del_el

Edit report at https://bugs.php.net/bug.php?id=68252&edit=1 ID: 68252 Comment by: bugs at milos dot nz Reported by: bugs at milos dot nz Summary: segfault in Zend/zend_hash.c in function _zend_hash_del_el Status: Open Type: Bug Package: Reproducible crash Operating System: Linux 3.16 (Gentoo) PHP Version: master-Git-2014-10-17 (Git) Block user comment: N Private report: N New Comment: 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 = 0 Previous Comments: ------------------------------------------------------------------------ [2014-10-21 10:10:14] bugs at milos dot nz "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> ------------------------------------------------------------------------ [2014-10-21 09:34:07] laruence@php.net hmmm, could you please use bt -full ? I needs to see what i is, and what ht->arData is thanks ------------------------------------------------------------------------ [2014-10-21 02:51:17] bugs at milos dot nz ==22449== Memcheck, a memory error detector ==22449== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. ==22449== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info ==22449== Command: sapi/cgi/php-cgi /home/user/example.com/www/public_html/index.php ==22449== X-Powered-By: PHP/7.0.0-dev ... snip ... ... more headers here ... ... snip ... <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en-US"> <head> ... snip ... ... wordpress output here ... ... snip ... </tr> </table><!-- / layout --> </div><!-- / container --> </div><!-- / wrapper --> </body> </html>==22420== Invalid read of size 4 ==22420== at 0x745669: _zend_hash_del_el (zend_hash.c:658) ==22420== by 0x745669: zend_hash_apply_deleter (zend_hash.c:973) ==22420== by 0x74A218: zend_hash_reverse_apply (zend_hash.c:1133) ==22420== by 0x7299E7: shutdown_executor (zend_execute_API.c:347) ==22420== by 0x739DA6: zend_deactivate (zend.c:883) ==22420== by 0x6DEDFD: php_request_shutdown (main.c:1859) ==22420== by 0x483513: main (cgi_main.c:2515) ==22420== Address 0x200e712e1c is not stack'd, malloc'd or (recently) free'd ==22420== ==22420== ==22420== Process terminating with default action of signal 11 (SIGSEGV): dumping core ==22420== Access not within mapped region at address 0x200E712E1C ==22420== at 0x745669: _zend_hash_del_el (zend_hash.c:658) ==22420== by 0x745669: zend_hash_apply_deleter (zend_hash.c:973) ==22420== by 0x74A218: zend_hash_reverse_apply (zend_hash.c:1133) ==22420== by 0x7299E7: shutdown_executor (zend_execute_API.c:347) ==22420== by 0x739DA6: zend_deactivate (zend.c:883) ==22420== by 0x6DEDFD: php_request_shutdown (main.c:1859) ==22420== by 0x483513: main (cgi_main.c:2515) ==22420== If you believe this happened as a result of a stack ==22420== overflow in your program's main thread (unlikely but ==22420== possible), you can try to increase the size of the ==22420== main thread stack using the --main-stacksize= flag. ==22420== The main thread stack size used in this run was 8388608. ==22420== ==22420== HEAP SUMMARY: ==22420== in use at exit: 8,710,274 bytes in 68,379 blocks ==22420== total heap usage: 463,170 allocs, 394,791 frees, 170,725,487 bytes allocated ==22420== ==22420== LEAK SUMMARY: ==22420== definitely lost: 18,056 bytes in 367 blocks ==22420== indirectly lost: 13,600 bytes in 28 blocks ==22420== possibly lost: 6,328 bytes in 17 blocks ==22420== still reachable: 8,672,290 bytes in 67,967 blocks ==22420== suppressed: 0 bytes in 0 blocks ==22420== Rerun with --leak-check=full to see details of leaked memory ==22420== ==22420== For counts of detected and suppressed errors, rerun with: -v ==22420== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0) Segmentation fault ------------------------------------------------------------------------ [2014-10-20 15:33:15] laruence@php.net could you please run wordpress index.php with valgrind.. like: USE_ZEND_ALLOC=0 valgrind path-to-php/bin/php wordpress/index.php and paste the output out? thanks ------------------------------------------------------------------------ [2014-10-17 14:07:50] 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-pd! o' '--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-pd! o-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' ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=68252&edit=1