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From 847a645152f5ebc10ac63b74b604d0c1a79fae40 Mon Sep 17 00:00:00 2001
From: Samanta Navarro <ferivoz@riseup.net>
Date: Sat, 22 Jan 2022 17:48:00 +0100
Subject: [PATCH 1/3] lib: Detect and prevent integer overflow in XML_GetBuffer
(CVE-2022-23852)
---
expat/lib/xmlparse.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
index d54af683..5ce31402 100644
--- a/expat/lib/xmlparse.c
+++ b/expat/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
From acf956f14bf79a5e6383a969aaffec98bfbc2e44 Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Sun, 23 Jan 2022 18:17:04 +0100
Subject: [PATCH 2/3] tests: Cover integer overflow in XML_GetBuffer
(CVE-2022-23852)
---
expat/tests/runtests.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/expat/tests/runtests.c b/expat/tests/runtests.c
index e89e8220..579dad1a 100644
--- a/expat/tests/runtests.c
+++ b/expat/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);
From 99cec436fbd9444f57ee74ca8ae4c0a13e561a4f Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Sat, 22 Jan 2022 17:49:17 +0100
Subject: [PATCH 3/3] Changes: Document CVE-2022-23852
---
expat/Changes | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/expat/Changes b/expat/Changes
index 7540d38c..64d75d05 100644
--- a/expat/Changes
+++ b/expat/Changes
@@ -2,6 +2,18 @@ NOTE: We are looking for help with a few things:
https://github.com/libexpat/libexpat/labels/help%20wanted
If you can help, please get in touch. Thanks!
+Release x.x.x xxx xxxxxxx xx xxxx
+ Security fixes:
+ #550 CVE-2022-23852 -- Fix signed integer overflow
+ (undefined behavior) in function XML_GetBuffer
+ (that is also called by function XML_Parse internally)
+ for when XML_CONTEXT_BYTES is defined to >0 (which is both
+ common and default).
+ Impact is denial of service or more.
+
+ Special thanks to:
+ Samanta Navarro
+
Release 2.4.3 Sun January 16 2022
Security fixes:
#531 #534 CVE-2021-45960 -- Fix issues with left shifts by >=29 places
|
