php 5.3.26 heap corruption in the XML parser

2013-07-11 / 2013-08-10
Credit: johannes
Risk: High
Local: Yes
Remote: Yes
CWE: CWE-119


CVSS Base Score: 6.8/10
Impact Subscore: 6.4/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

Description: ------------ Badly formed XML might corrupt the heap. Test script: --------------- <?php xml_parse_into_struct(xml_parser_create_ns(), str_repeat("<blah>", 1000), $a); Expected result: ---------------- Warning: xml_parse_into_struct(): Maximum depth exceeded - Results truncated Actual result: -------------- heap corruption diff --git a/ext/xml/xml.c b/ext/xml/xml.c index 1f0480b..9f0bc30 100644 --- a/ext/xml/xml.c +++ b/ext/xml/xml.c @@ -427,7 +427,7 @@ static void xml_parser_dtor(zend_rsrc_list_entry *rsrc TSRMLS_DC) } if (parser->ltags) { int inx; - for (inx = 0; inx < parser->level; inx++) + for (inx = 0; ((inx < parser->level) && (inx < XML_MAXLEVEL)); inx++) efree(parser->ltags[ inx ]); efree(parser->ltags); } @@ -905,45 +905,50 @@ void _xml_startElementHandler(void *userData, const XML_Char *name, const XML_Ch } if (parser->data) { - zval *tag, *atr; - int atcnt = 0; + if (parser->level <= XML_MAXLEVEL) { + zval *tag, *atr; + int atcnt = 0; - MAKE_STD_ZVAL(tag); - MAKE_STD_ZVAL(atr); + MAKE_STD_ZVAL(tag); + MAKE_STD_ZVAL(atr); - array_init(tag); - array_init(atr); + array_init(tag); + array_init(atr); - _xml_add_to_info(parser,((char *) tag_name) + parser->toffset); + _xml_add_to_info(parser,((char *) tag_name) + parser->toffset); - add_assoc_string(tag,"tag",((char *) tag_name) + parser->toffset,1); /* cast to avoid gcc-warning */ - add_assoc_string(tag,"type","open",1); - add_assoc_long(tag,"level",parser->level); + add_assoc_string(tag,"tag",((char *) tag_name) + parser->toffset,1); /* cast to avoid gcc-warning */ + add_assoc_string(tag,"type","open",1); + add_assoc_long(tag,"level",parser->level); - parser->ltags[parser->level-1] = estrdup(tag_name); - parser->lastwasopen = 1; + parser->ltags[parser->level-1] = estrdup(tag_name); + parser->lastwasopen = 1; - attributes = (const XML_Char **) attrs; + attributes = (const XML_Char **) attrs; - while (attributes && *attributes) { - att = _xml_decode_tag(parser, attributes[0]); - val = xml_utf8_decode(attributes[1], strlen(attributes[1]), &val_len, parser->target_encoding); - - add_assoc_stringl(atr,att,val,val_len,0); + while (attributes && *attributes) { + att = _xml_decode_tag(parser, attributes[0]); + val = xml_utf8_decode(attributes[1], strlen(attributes[1]), &val_len, parser->target_encoding); - atcnt++; - attributes += 2; + add_assoc_stringl(atr,att,val,val_len,0); - efree(att); - } + atcnt++; + attributes += 2; - if (atcnt) { - zend_hash_add(Z_ARRVAL_P(tag),"attributes",sizeof("attributes"),&atr,sizeof(zval*),NULL); - } else { - zval_ptr_dtor(&atr); - } + efree(att); + } + + if (atcnt) { + zend_hash_add(Z_ARRVAL_P(tag),"attributes",sizeof("attributes"),&atr,sizeof(zval*),NULL); + } else { + zval_ptr_dtor(&atr); + } - zend_hash_next_index_insert(Z_ARRVAL_P(parser->data),&tag,sizeof(zval*),(void *) &parser->ctag); + zend_hash_next_index_insert(Z_ARRVAL_P(parser->data),&tag,sizeof(zval*),(void *) &parser->ctag); + } else if (parser->level == (XML_MAXLEVEL + 1)) { + TSRMLS_FETCH(); + php_error_docref(NULL TSRMLS_CC, E_WARNING, "Maximum depth exceeded - Results truncated"); + } } efree(tag_name); @@ -995,7 +1000,7 @@ void _xml_endElementHandler(void *userData, const XML_Char *name) efree(tag_name); - if (parser->ltags) { + if ((parser->ltags) && (parser->level <= XML_MAXLEVEL)) { efree(parser->ltags[parser->level-1]); } @@ -1079,18 +1084,23 @@ void _xml_characterDataHandler(void *userData, const XML_Char *s, int len) } } - MAKE_STD_ZVAL(tag); - - array_init(tag); - - _xml_add_to_info(parser,parser->ltags[parser->level-1] + parser->toffset); + if (parser->level <= XML_MAXLEVEL) { + MAKE_STD_ZVAL(tag); - add_assoc_string(tag,"tag",parser->ltags[parser->level-1] + parser->toffset,1); - add_assoc_string(tag,"value",decoded_value,0); - add_assoc_string(tag,"type","cdata",1); - add_assoc_long(tag,"level",parser->level); + array_init(tag); - zend_hash_next_index_insert(Z_ARRVAL_P(parser->data),&tag,sizeof(zval*),NULL); + _xml_add_to_info(parser,parser->ltags[parser->level-1] + parser->toffset); + + add_assoc_string(tag,"tag",parser->ltags[parser->level-1] + parser->toffset,1); + add_assoc_string(tag,"value",decoded_value,0); + add_assoc_string(tag,"type","cdata",1); + add_assoc_long(tag,"level",parser->level); + + zend_hash_next_index_insert(Z_ARRVAL_P(parser->data),&tag,sizeof(zval*),NULL); + } else if (parser->level == (XML_MAXLEVEL + 1)) { + TSRMLS_FETCH(); + php_error_docref(NULL TSRMLS_CC, E_WARNING, "Maximum depth exceeded - Results truncated"); + } } } else { efree(decoded_value);

References:

https://bugs.php.net/bug.php?id=65236


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