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[2016-04-25 04:55 UTC] fernando at null-life dot com
Description:
------------
Run test script with PHP/ASAN. I'm marking it as security since parsing xml coming from user is a common task, so apologies in advance if it's not security relevant.
(gdb) b xml.c:992
Breakpoint 1 at 0x83a3ae5: file /home/fmunozs/phpgit/php56dbg/ext/xml/xml.c, line 992.
(gdb) r
Breakpoint 1, _xml_characterDataHandler (userData=0xb5f5bba4, s=0x8d185e5 "aaaaaaaaaa", len=10)
at /home/fmunozs/phpgit/php56dbg/ext/xml/xml.c:992
992 _xml_add_to_info(parser,parser->ltags[parser->level-1] + parser->toffset);
(gdb) print parser
$1 = (xml_parser *) 0xb5f5bba4
(gdb) print parser->ltags
$2 = (char **) 0xb5f5c894
(gdb) print parser->ltags[parser->level-1]
$3 = 0x5c7efff0 <error: Cannot access memory at address 0x5c7efff0>
(gdb) print parser->ltags[parser->level]
$4 = 0x0
(gdb) print parser->ltags
$5 = (char **) 0xb5f5c894
(gdb) print parser->level
$8 = 0
(gdb) print parser->ltags[parser->level-1] + parser->toffset
$9 = 0x5c7efff0 <error: Cannot access memory at address 0x5c7efff0>
parser->level is 0 and line 992 is trying to access -1 element.
Test script:
---------------
<?php
$var1=xml_parser_create_ns();
$var2="<xss>";
xml_parse($var1, $var2);
$var2=str_repeat("a", 10);
$var3=[];
$var4=[];
xml_parse_into_struct($var1, $var2, $var3, $var4);
var_dump($var3);
Expected result:
----------------
No crash
Actual result:
--------------
=================================================================
==4221==ERROR: AddressSanitizer: SEGV on unknown address 0x0000001d (pc 0xb6dc6256 bp 0xbfba8e18 sp 0xbfba89a4 T0)
#0 0xb6dc6255 (/lib/i386-linux-gnu/libc.so.6+0x7c255)
#1 0xb71e7655 in __interceptor_strlen (/usr/lib/i386-linux-gnu/libasan.so.2+0x6a655)
#2 0x90e321f in _xml_add_to_info /home/fmunozs/phpgit/php56/ext/xml/xml.c:740
#3 0x90ef305 in _xml_characterDataHandler /home/fmunozs/phpgit/php56/ext/xml/xml.c:992
#4 0x90ff63b in _cdata_handler /home/fmunozs/phpgit/php56/ext/xml/compat.c:274
#5 0xb6f33ec4 in xmlParseCharData (/usr/lib/i386-linux-gnu/libxml2.so.2+0x34ec4)
#6 0xb6f4461c (/usr/lib/i386-linux-gnu/libxml2.so.2+0x4561c)
#7 0xb6f44f62 in xmlParseChunk (/usr/lib/i386-linux-gnu/libxml2.so.2+0x45f62)
#8 0x9103efb in php_XML_Parse /home/fmunozs/phpgit/php56/ext/xml/compat.c:605
#9 0x90e0e8e in zif_xml_parse_into_struct /home/fmunozs/phpgit/php56/ext/xml/xml.c:1499
#10 0x9a7dbe8 in zend_do_fcall_common_helper_SPEC /home/fmunozs/phpgit/php56/Zend/zend_vm_execute.h:558
#11 0x96417e6 in execute_ex /home/fmunozs/phpgit/php56/Zend/zend_vm_execute.h:363
#12 0x9a6de98 in zend_execute /home/fmunozs/phpgit/php56/Zend/zend_vm_execute.h:388
#13 0x9472029 in zend_execute_scripts /home/fmunozs/phpgit/php56/Zend/zend.c:1341
#14 0x91ae13b in php_execute_script /home/fmunozs/phpgit/php56/main/main.c:2613
#15 0x9a8795a in do_cli /home/fmunozs/phpgit/php56/sapi/cli/php_cli.c:994
#16 0x808a502 in main /home/fmunozs/phpgit/php56/sapi/cli/php_cli.c:1378
#17 0xb6d62645 in __libc_start_main (/lib/i386-linux-gnu/libc.so.6+0x18645)
#18 0x808aaba (/home/fmunozs/phpgit/php56/sapi/cli/php+0x808aaba)
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV ??:0 ??
==4221==ABORTING
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Using the test script in this bug report with PHP 7.1.0-dev (cli) (built: May 6 2016 15:15:38), I'm seeing a null pointer deref: ==126942== Invalid read of size 1 ==126942== at 0x4C2C1A2: strlen (vg_replace_strmem.c:412) ==126942== by 0x11DC7AF: _xml_add_to_info (xml.c:687) ==126942== by 0x11DC7AF: _xml_characterDataHandler (xml.c:924) ==126942== by 0x5BEB1B4: xmlParseCharData (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1) ==126942== by 0x5BF84CB: xmlParseTryOrFinish (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1) ==126942== by 0x5BF8E2D: xmlParseChunk (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1) ==126942== by 0x11E7098: php_XML_Parse (compat.c:596) ==126942== by 0x11D39E1: zif_xml_parse_into_struct (xml.c:1450) ==126942== by 0x169757E: ZEND_DO_ICALL_SPEC_RETVAL_UNUSED_HANDLER (zend_vm_execute.h:615) ==126942== by 0x1645B42: execute_ex (zend_vm_execute.h:425) ==126942== by 0x188EFE0: zend_execute (zend_vm_execute.h:470) ==126942== by 0x145EDD7: zend_execute_scripts (zend.c:1427) ==126942== by 0x120AD3F: php_execute_script (main.c:2492) ==126942== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==126942== ==126942== ==126942== Process terminating with default action of signal 11 (SIGSEGV) ==126942== Access not within mapped region at address 0x0 ==126942== at 0x4C2C1A2: strlen (vg_replace_strmem.c:412) ==126942== by 0x11DC7AF: _xml_add_to_info (xml.c:687) ==126942== by 0x11DC7AF: _xml_characterDataHandler (xml.c:924) ==126942== by 0x5BEB1B4: xmlParseCharData (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1) ==126942== by 0x5BF84CB: xmlParseTryOrFinish (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1) ==126942== by 0x5BF8E2D: xmlParseChunk (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1) ==126942== by 0x11E7098: php_XML_Parse (compat.c:596) ==126942== by 0x11D39E1: zif_xml_parse_into_struct (xml.c:1450) ==126942== by 0x169757E: ZEND_DO_ICALL_SPEC_RETVAL_UNUSED_HANDLER (zend_vm_execute.h:615) ==126942== by 0x1645B42: execute_ex (zend_vm_execute.h:425) ==126942== by 0x188EFE0: zend_execute (zend_vm_execute.h:470) ==126942== by 0x145EDD7: zend_execute_scripts (zend.c:1427) ==126942== by 0x120AD3F: php_execute_script (main.c:2492) ==126942== If you believe this happened as a result of a stack ==126942== overflow in your program's main thread (unlikely but ==126942== possible), you can try to increase the size of the ==126942== main thread stack using the --main-stacksize= flag. ==126942== The main thread stack size used in this run was 8388608. Segmentation fault #0 strlen () at ../sysdeps/x86_64/strlen.S:106 #1 0x00000000011dc7b0 in _xml_add_to_info (name=0x0, parser=0x7ffff6078000) at /home/geeknik/php-src/ext/xml/xml.c:687 #2 _xml_characterDataHandler (userData=0x7ffff6078000, s=<optimized out>, len=<optimized out>) at /home/geeknik/php-src/ext/xml/xml.c:924 #3 0x00007ffff6d451b5 in xmlParseCharData__internal_alias (ctxt=ctxt@entry=0x2138850, cdata=cdata@entry=0) at ../../parser.c:4579 #4 0x00007ffff6d524cc in xmlParseTryOrFinish (ctxt=ctxt@entry=0x2138850, terminate=terminate@entry=1) at ../../parser.c:11658 #5 0x00007ffff6d52e2e in xmlParseChunk__internal_alias (ctxt=0x2138850, chunk=0x7ffff60601f8 "aaaaaaaaaa", size=10, terminate=terminate@entry=1) at ../../parser.c:12397 #6 0x00000000011e7099 in php_XML_Parse (parser=0x7ffff6085000, data=<optimized out>, data_len=<optimized out>, is_final=is_final@entry=1) at /home/geeknik/php-src/ext/xml/compat.c:596 #7 0x00000000011d39e2 in zif_xml_parse_into_struct (execute_data=<optimized out>, return_value=0x7fffffffa8c0) at /home/geeknik/php-src/ext/xml/xml.c:1450 #8 0x000000000169757f in ZEND_DO_ICALL_SPEC_RETVAL_UNUSED_HANDLER () at /home/geeknik/php-src/Zend/zend_vm_execute.h:615 #9 0x0000000001645b43 in execute_ex (ex=<optimized out>) at /home/geeknik/php-src/Zend/zend_vm_execute.h:425 #10 0x000000000188efe1 in zend_execute (op_array=op_array@entry=0x7ffff6086280, return_value=return_value@entry=0x0) at /home/geeknik/php-src/Zend/zend_vm_execute.h:470 #11 0x000000000145edd8 in zend_execute_scripts (type=type@entry=8, retval=retval@entry=0x0, file_count=-167698384, file_count@entry=3) at /home/geeknik/php-src/Zend/zend.c:1427 #12 0x000000000120ad40 in php_execute_script (primary_file=0x7fffffffcf20) at /home/geeknik/php-src/main/main.c:2492 #13 0x000000000189ae95 in do_cli (argc=0, argv=0x8) at /home/geeknik/php-src/sapi/cli/php_cli.c:982 #14 0x0000000000450dd1 in main (argc=0, argv=0x8) at /home/geeknik/php-src/sapi/cli/php_cli.c:1352