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CVE-2022-23852 expat: integer overflow in function XML_GetBuffer 

Resolves: CVE-2022-23852
This commit is contained in:
Tomas Korbar 2022-02-10 14:17:38 +01:00
parent 21e8e5c32d
commit 66503cfe5b
2 changed files with 69 additions and 1 deletions
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62
expat-2.2.10-Detect-and-prevent-integer-overflow-in-XML_GetBuffer.patch Normal file
View File

@ -0,0 +1,62 @@
diff --git a/lib/xmlparse.c b/lib/xmlparse.c
index d54af683..5ce31402 100644
--- a/lib/xmlparse.c
+++ b/lib/xmlparse.c
@@ -2067,6 +2067,11 @@ XML_GetBuffer(XML_Parser parser, int len) {
keep = (int)EXPAT_SAFE_PTR_DIFF(parser->m_bufferPtr, parser->m_buffer);
if (keep > XML_CONTEXT_BYTES)
keep = XML_CONTEXT_BYTES;
+ /* Detect and prevent integer overflow */
+ if (keep > INT_MAX - neededSize) {
+ parser->m_errorCode = XML_ERROR_NO_MEMORY;
+ return NULL;
+ }
neededSize += keep;
#endif /* defined XML_CONTEXT_BYTES */
if (neededSize
diff --git a/tests/runtests.c b/tests/runtests.c
index e89e8220..579dad1a 100644
--- a/tests/runtests.c
+++ b/tests/runtests.c
@@ -3847,6 +3847,30 @@ START_TEST(test_get_buffer_2) {
}
END_TEST
+/* Test for signed integer overflow CVE-2022-23852 */
+#if defined(XML_CONTEXT_BYTES)
+START_TEST(test_get_buffer_3_overflow) {
+ XML_Parser parser = XML_ParserCreate(NULL);
+ assert(parser != NULL);
+
+ const char *const text = "\n";
+ const int expectedKeepValue = (int)strlen(text);
+
+ // After this call, variable "keep" in XML_GetBuffer will
+ // have value expectedKeepValue
+ if (XML_Parse(parser, text, (int)strlen(text), XML_FALSE /* isFinal */)
+ == XML_STATUS_ERROR)
+ xml_failure(parser);
+
+ assert(expectedKeepValue > 0);
+ if (XML_GetBuffer(parser, INT_MAX - expectedKeepValue + 1) != NULL)
+ fail("enlarging buffer not failed");
+
+ XML_ParserFree(parser);
+}
+END_TEST
+#endif // defined(XML_CONTEXT_BYTES)
+
/* Test position information macros */
START_TEST(test_byte_info_at_end) {
const char *text = "<doc></doc>";
@@ -11731,6 +11755,9 @@ make_suite(void) {
tcase_add_test(tc_basic, test_empty_parse);
tcase_add_test(tc_basic, test_get_buffer_1);
tcase_add_test(tc_basic, test_get_buffer_2);
+#if defined(XML_CONTEXT_BYTES)
+ tcase_add_test(tc_basic, test_get_buffer_3_overflow);
+#endif
tcase_add_test(tc_basic, test_byte_info_at_end);
tcase_add_test(tc_basic, test_byte_info_at_error);
tcase_add_test(tc_basic, test_byte_info_at_cdata);

8
expat.spec
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@ -3,7 +3,7 @@
Summary: An XML parser library
Name: expat
Version: %(echo %{unversion} | sed 's/_/./g')
Release: 8%{?dist}
Release: 9%{?dist}
Source: https://github.com/libexpat/libexpat/archive/R_%{unversion}.tar.gz#/expat-%{version}.tar.gz
URL: https://libexpat.github.io/
License: MIT
@ -13,6 +13,7 @@ Patch0: expat-2.2.10-prevent-integer-overflow-in-doProlog.patch
Patch1: expat-2.2.10-Prevent-more-integer-overflows.patch
Patch2: expat-2.2.10-Prevent-integer-overflow-on-m_groupSize-in-function.patch
Patch3: expat-2.2.10-Detect-and-prevent-troublesome-left-shifts.patch
Patch4: expat-2.2.10-Detect-and-prevent-integer-overflow-in-XML_GetBuffer.patch
%description
This is expat, the C library for parsing XML, written by James Clark. Expat
@ -44,6 +45,7 @@ Install it if you need to link statically with expat.
%patch1 -p1 -b .CVE-2022-22822-CVE-2022-22827
%patch2 -p1 -b .CVE-2021-46143
%patch3 -p1 -b .CVE-2021-45960
%patch4 -p1 -b .CVE-2022-23852
sed -i 's/install-data-hook/do-nothing-please/' lib/Makefile.am
./buildconf.sh
@ -81,6 +83,10 @@ make check
%{_libdir}/lib*.a
%changelog
* Thu Feb 10 2022 Tomas Korbar <tkorbar@redhat.com> - 2.2.10-9
- CVE-2022-23852 expat: integer overflow in function XML_GetBuffer
- Resolves: CVE-2022-23852
* Thu Feb 10 2022 Tomas Korbar <tkorbar@redhat.com> - 2.2.10-8
- CVE-2021-45960 expat: Large number of prefixed XML attributes on a single tag can crash libexpat
- Resolves: CVE-2021-45960