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Fix parsing of large tokens

This commit is contained in:
Tomas Korbar 2024-02-13 16:37:45 +01:00 committed by root
parent e4844ef25b
commit d83af87ffc
4 changed files with 1663 additions and 1 deletions
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1
.expat.metadata Normal file
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03d9882ede56aa48919fbf50fe17614630257a82 expat-2.5.0.tar.gz

1466
expat-2.5.0-CVE-2023-52425.patch Normal file
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expat-2.5.0-CVE-2024-28757.patch Normal file
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commit cd3b344e0dbd19a812d0b4f34f9d089ed7c5c411
Author: Tomas Korbar <tkorbar@redhat.com>
Date: Tue Mar 19 15:12:18 2024 +0100
Fix CVE-2024-28757
Upstream PRs #841 and #842
diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
index 2ae64e9..0896b16 100644
--- a/expat/lib/xmlparse.c
+++ b/expat/lib/xmlparse.c
@@ -6164,7 +6164,7 @@ storeEntityValue(XML_Parser parser, const ENCODING *enc,
dtd->keepProcessing = dtd->standalone;
goto endEntityValue;
}
- if (entity->open) {
+ if (entity->open || (entity == parser->m_declEntity)) {
if (enc == parser->m_encoding)
parser->m_eventPtr = entityTextPtr;
result = XML_ERROR_RECURSIVE_ENTITY_REF;
@@ -7680,6 +7680,8 @@ copyString(const XML_Char *s, const XML_Memory_Handling_Suite *memsuite) {
static float
accountingGetCurrentAmplification(XML_Parser rootParser) {
+ // 1.........1.........12 => 22
+ const size_t lenOfShortestInclude = sizeof("<!ENTITY a SYSTEM 'b'>") - 1;
const XmlBigCount countBytesOutput
= rootParser->m_accounting.countBytesDirect
+ rootParser->m_accounting.countBytesIndirect;
@@ -7687,7 +7689,9 @@ accountingGetCurrentAmplification(XML_Parser rootParser) {
= rootParser->m_accounting.countBytesDirect
? (countBytesOutput
/ (float)(rootParser->m_accounting.countBytesDirect))
- : 1.0f;
+ : ((lenOfShortestInclude
+ + rootParser->m_accounting.countBytesIndirect)
+ / (float)lenOfShortestInclude);
assert(! rootParser->m_parentParser);
return amplificationFactor;
}
diff --git a/expat/tests/runtests.c b/expat/tests/runtests.c
index 941f61d..93adc45 100644
--- a/expat/tests/runtests.c
+++ b/expat/tests/runtests.c
@@ -1788,6 +1788,48 @@ START_TEST(test_wfc_no_recursive_entity_refs) {
}
END_TEST
+START_TEST(test_recursive_external_parameter_entity_2) {
+ struct TestCase {
+ const char *doc;
+ enum XML_Status expectedStatus;
+ };
+
+ struct TestCase cases[] = {
+ {"<!ENTITY % p1 '%p1;'>", XML_STATUS_ERROR},
+ {"<!ENTITY % p1 '%p1;'>"
+ "<!ENTITY % p1 'first declaration wins'>",
+ XML_STATUS_ERROR},
+ {"<!ENTITY % p1 'first declaration wins'>"
+ "<!ENTITY % p1 '%p1;'>",
+ XML_STATUS_OK},
+ {"<!ENTITY % p1 '&#37;p1;'>", XML_STATUS_OK},
+ };
+
+ for (size_t i = 0; i < sizeof(cases) / sizeof(cases[0]); i++) {
+ const char *const doc = cases[i].doc;
+ const enum XML_Status expectedStatus = cases[i].expectedStatus;
+
+ XML_Parser parser = XML_ParserCreate(NULL);
+ assert_true(parser != NULL);
+
+ XML_Parser ext_parser = XML_ExternalEntityParserCreate(parser, NULL, NULL);
+ assert_true(ext_parser != NULL);
+
+ const enum XML_Status actualStatus
+ = _XML_Parse_SINGLE_BYTES(ext_parser, doc, (int)strlen(doc), XML_TRUE);
+
+ assert_true(actualStatus == expectedStatus);
+ if (actualStatus != XML_STATUS_OK) {
+ assert_true(XML_GetErrorCode(ext_parser)
+ == XML_ERROR_RECURSIVE_ENTITY_REF);
+ }
+
+ XML_ParserFree(ext_parser);
+ XML_ParserFree(parser);
+ }
+}
+END_TEST
+
/* Test incomplete external entities are faulted */
START_TEST(test_ext_entity_invalid_parse) {
const char *text = "<!DOCTYPE doc [\n"
@@ -12719,6 +12761,60 @@ START_TEST(test_helper_unsigned_char_to_printable) {
fail("unsignedCharToPrintable result mistaken");
}
END_TEST
+
+START_TEST(test_amplification_isolated_external_parser) {
+ // NOTE: Length 44 is precisely twice the length of "<!ENTITY a SYSTEM 'b'>"
+ // (22) that is used in function accountingGetCurrentAmplification in
+ // xmlparse.c.
+ // 1.........1.........1.........1.........1..4 => 44
+ const char doc[] = "<!ENTITY % p1 '123456789_123456789_1234567'>";
+ const int docLen = (int)sizeof(doc) - 1;
+ const float maximumToleratedAmplification = 2.0f;
+
+ struct TestCase {
+ int offsetOfThreshold;
+ enum XML_Status expectedStatus;
+ };
+
+ struct TestCase cases[] = {
+ {-2, XML_STATUS_ERROR}, {-1, XML_STATUS_ERROR}, {0, XML_STATUS_ERROR},
+ {+1, XML_STATUS_OK}, {+2, XML_STATUS_OK},
+ };
+
+ for (size_t i = 0; i < sizeof(cases) / sizeof(cases[0]); i++) {
+ const int offsetOfThreshold = cases[i].offsetOfThreshold;
+ const enum XML_Status expectedStatus = cases[i].expectedStatus;
+ const unsigned long long activationThresholdBytes
+ = docLen + offsetOfThreshold;
+
+ XML_Parser parser = XML_ParserCreate(NULL);
+ assert_true(parser != NULL);
+
+ assert_true(XML_SetBillionLaughsAttackProtectionMaximumAmplification(
+ parser, maximumToleratedAmplification)
+ == XML_TRUE);
+ assert_true(XML_SetBillionLaughsAttackProtectionActivationThreshold(
+ parser, activationThresholdBytes)
+ == XML_TRUE);
+
+ XML_Parser ext_parser = XML_ExternalEntityParserCreate(parser, NULL, NULL);
+ assert_true(ext_parser != NULL);
+
+ const enum XML_Status actualStatus
+ = _XML_Parse_SINGLE_BYTES(ext_parser, doc, docLen, XML_TRUE);
+
+ assert_true(actualStatus == expectedStatus);
+ if (actualStatus != XML_STATUS_OK) {
+ assert_true(XML_GetErrorCode(ext_parser)
+ == XML_ERROR_AMPLIFICATION_LIMIT_BREACH);
+ }
+
+ XML_ParserFree(ext_parser);
+ XML_ParserFree(parser);
+ }
+}
+END_TEST
+
#endif // defined(XML_DTD)
static Suite *
@@ -12871,6 +12967,8 @@ make_suite(void) {
tcase_add_test__ifdef_xml_dtd(tc_basic, test_skipped_parameter_entity);
tcase_add_test__ifdef_xml_dtd(tc_basic,
test_recursive_external_parameter_entity);
+ tcase_add_test__ifdef_xml_dtd(tc_basic,
+ test_recursive_external_parameter_entity_2);
tcase_add_test(tc_basic, test_undefined_ext_entity_in_external_dtd);
tcase_add_test(tc_basic, test_suspend_xdecl);
tcase_add_test(tc_basic, test_abort_epilog);
@@ -13120,6 +13218,7 @@ make_suite(void) {
tcase_add_test(tc_accounting, test_accounting_precision);
tcase_add_test(tc_accounting, test_billion_laughs_attack_protection_api);
tcase_add_test(tc_accounting, test_helper_unsigned_char_to_printable);
+ tcase_add_test(tc_accounting, test_amplification_isolated_external_parser);
#endif
return s;

25
expat.spec
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@ -3,12 +3,16 @@
Summary: An XML parser library
Name: expat
Version: %(echo %{unversion} | sed 's/_/./g')
Release: 1%{?dist}
Release: 2%{?dist}
Source: https://github.com/libexpat/libexpat/archive/R_%{unversion}.tar.gz#/expat-%{version}.tar.gz
URL: https://libexpat.github.io/
License: MIT
BuildRequires: autoconf, libtool, xmlto, gcc-c++
BuildRequires: make
# https://issues.redhat.com/browse/RHEL-24227
Patch0: expat-2.5.0-CVE-2023-52425.patch
# https://issues.redhat.com/browse/RHEL-28700
Patch1: expat-2.5.0-CVE-2024-28757.patch
%description
This is expat, the C library for parsing XML, written by James Clark. Expat
@ -36,6 +40,10 @@ Install it if you need to link statically with expat.
%prep
%setup -q -n libexpat-R_%{unversion}/expat
pushd ..
%patch0 -p1 -b .CVE-2023-52425
%patch1 -p1 -b .CVE-2024-28757
popd
sed -i 's/install-data-hook/do-nothing-please/' lib/Makefile.am
./buildconf.sh
@ -52,6 +60,15 @@ export DOCBOOK_TO_MAN="xmlto man --skip-validation"
rm -f $RPM_BUILD_ROOT%{_libdir}/*.la
%check
bash -c "for i in {1..500000}; do printf AAAAAAAAAAAAAAAAAAAA >> achars.txt; done"
for testfile in ../testdata/largefiles/aaaaaa_*; do
first_part="$(sed 's/\(.*\)ACHARS.*/\1/g' $testfile)"
second_part="$(sed 's/.*ACHARS\(.*\)/\1/g' $testfile)"
printf "$first_part" > "$testfile"
cat achars.txt >> "$testfile"
printf "$second_part" >> "$testfile"
done
make check
%ldconfig_scriptlets
@ -74,6 +91,12 @@ make check
%{_libdir}/lib*.a
%changelog
* Tue Feb 13 2024 Tomas Korbar <tkorbar@redhat.com> - 2.5.0-2
- Fix parsing of large tokens
- Reject direct parameter entity recursion
- Resolves: RHEL-29699
- Resolves: RHEL-29696
* Thu Nov 10 2022 Tomas Korbar <tkorbar@redhat.com> - 2.5.0-1
- Rebase to version 2.5.0
- Resolves: CVE-2022-43680