From ee2a5b50e7d1940ba8745715b62ceb9efd3a96da Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Tue, 8 Feb 2022 17:37:14 +0100
Subject: [PATCH 1/5] lib: Drop unused macro UTF8_GET_NAMING
---
expat/lib/xmltok.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/lib/xmltok.c b/lib/xmltok.c
index a72200e8..3bddf125 100644
--- a/lib/xmltok.c
+++ b/lib/xmltok.c
@@ -98,11 +98,6 @@
+ ((((byte)[1]) & 3) << 1) + ((((byte)[2]) >> 5) & 1)] \
& (1u << (((byte)[2]) & 0x1F)))
-#define UTF8_GET_NAMING(pages, p, n) \
- ((n) == 2 \
- ? UTF8_GET_NAMING2(pages, (const unsigned char *)(p)) \
- : ((n) == 3 ? UTF8_GET_NAMING3(pages, (const unsigned char *)(p)) : 0))
-
/* Detection of invalid UTF-8 sequences is based on Table 3.1B
of Unicode 3.2: http://www.unicode.org/unicode/reports/tr28/
with the additional restriction of not allowing the Unicode
From 3f0a0cb644438d4d8e3294cd0b1245d0edb0c6c6 Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Tue, 8 Feb 2022 04:32:20 +0100
Subject: [PATCH 2/5] lib: Add missing validation of encoding (CVE-2022-25235)
---
expat/lib/xmltok_impl.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/lib/xmltok_impl.c b/lib/xmltok_impl.c
index 0430591b..64a3b2c1 100644
--- a/lib/xmltok_impl.c
+++ b/lib/xmltok_impl.c
@@ -69,7 +69,7 @@
case BT_LEAD##n: \
if (end - ptr < n) \
return XML_TOK_PARTIAL_CHAR; \
- if (! IS_NAME_CHAR(enc, ptr, n)) { \
+ if (IS_INVALID_CHAR(enc, ptr, n) || ! IS_NAME_CHAR(enc, ptr, n)) { \
*nextTokPtr = ptr; \
return XML_TOK_INVALID; \
} \
@@ -98,7 +98,7 @@
case BT_LEAD##n: \
if (end - ptr < n) \
return XML_TOK_PARTIAL_CHAR; \
- if (! IS_NMSTRT_CHAR(enc, ptr, n)) { \
+ if (IS_INVALID_CHAR(enc, ptr, n) || ! IS_NMSTRT_CHAR(enc, ptr, n)) { \
*nextTokPtr = ptr; \
return XML_TOK_INVALID; \
} \
@@ -1142,6 +1142,10 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
case BT_LEAD##n: \
if (end - ptr < n) \
return XML_TOK_PARTIAL_CHAR; \
+ if (IS_INVALID_CHAR(enc, ptr, n)) { \
+ *nextTokPtr = ptr; \
+ return XML_TOK_INVALID; \
+ } \
if (IS_NMSTRT_CHAR(enc, ptr, n)) { \
ptr += n; \
tok = XML_TOK_NAME; \
From c85a3025e7a1be086dc34e7559fbc543914d047f Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Wed, 9 Feb 2022 01:00:38 +0100
Subject: [PATCH 3/5] lib: Add comments to BT_LEAD* cases where encoding has
already been validated
---
expat/lib/xmltok_impl.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/lib/xmltok_impl.c b/lib/xmltok_impl.c
index 64a3b2c1..84ff35f9 100644
--- a/lib/xmltok_impl.c
+++ b/lib/xmltok_impl.c
@@ -1274,7 +1274,7 @@ PREFIX(attributeValueTok)(const ENCODING *enc, const char *ptr, const char *end,
switch (BYTE_TYPE(enc, ptr)) {
# define LEAD_CASE(n) \
case BT_LEAD##n: \
- ptr += n; \
+ ptr += n; /* NOTE: The encoding has already been validated. */ \
break;
LEAD_CASE(2)
LEAD_CASE(3)
@@ -1343,7 +1343,7 @@ PREFIX(entityValueTok)(const ENCODING *enc, const char *ptr, const char *end,
switch (BYTE_TYPE(enc, ptr)) {
# define LEAD_CASE(n) \
case BT_LEAD##n: \
- ptr += n; \
+ ptr += n; /* NOTE: The encoding has already been validated. */ \
break;
LEAD_CASE(2)
LEAD_CASE(3)
@@ -1522,7 +1522,7 @@ PREFIX(getAtts)(const ENCODING *enc, const char *ptr, int attsMax,
state = inName; \
}
# define LEAD_CASE(n) \
- case BT_LEAD##n: \
+ case BT_LEAD##n: /* NOTE: The encoding has already been validated. */ \
START_NAME ptr += (n - MINBPC(enc)); \
break;
LEAD_CASE(2)
@@ -1734,7 +1734,7 @@ PREFIX(nameLength)(const ENCODING *enc, const char *ptr) {
switch (BYTE_TYPE(enc, ptr)) {
# define LEAD_CASE(n) \
case BT_LEAD##n: \
- ptr += n; \
+ ptr += n; /* NOTE: The encoding has already been validated. */ \
break;
LEAD_CASE(2)
LEAD_CASE(3)
@@ -1779,7 +1779,7 @@ PREFIX(updatePosition)(const ENCODING *enc, const char *ptr, const char *end,
switch (BYTE_TYPE(enc, ptr)) {
# define LEAD_CASE(n) \
case BT_LEAD##n: \
- ptr += n; \
+ ptr += n; /* NOTE: The encoding has already been validated. */ \
pos->columnNumber++; \
break;
LEAD_CASE(2)
From 6a5510bc6b7efe743356296724e0b38300f05379 Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Tue, 8 Feb 2022 04:06:21 +0100
Subject: [PATCH 4/5] tests: Cover missing validation of encoding
(CVE-2022-25235)
---
expat/tests/runtests.c | 109 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)
diff --git a/tests/runtests.c b/tests/runtests.c
index bc5344b1..9b155b82 100644
--- a/tests/runtests.c
+++ b/tests/runtests.c
@@ -5998,6 +5998,105 @@ START_TEST(test_utf8_in_cdata_section_2) {
}
END_TEST
+START_TEST(test_utf8_in_start_tags) {
+ struct test_case {
+ bool goodName;
+ bool goodNameStart;
+ const char *tagName;
+ };
+
+ // The idea with the tests below is this:
+ // We want to cover 1-, 2- and 3-byte sequences, 4-byte sequences
+ // go to isNever and are hence not a concern.
+ //
+ // We start with a character that is a valid name character
+ // (or even name-start character, see XML 1.0r4 spec) and then we flip
+ // single bits at places where (1) the result leaves the UTF-8 encoding space
+ // and (2) we stay in the same n-byte sequence family.
+ //
+ // The flipped bits are highlighted in angle brackets in comments,
+ // e.g. "[<1>011 1001]" means we had [0011 1001] but we now flipped
+ // the most significant bit to 1 to leave UTF-8 encoding space.
+ struct test_case cases[] = {
+ // 1-byte UTF-8: [0xxx xxxx]
+ {true, true, "\x3A"}, // [0011 1010] = ASCII colon ':'
+ {false, false, "\xBA"}, // [<1>011 1010]
+ {true, false, "\x39"}, // [0011 1001] = ASCII nine '9'
+ {false, false, "\xB9"}, // [<1>011 1001]
+
+ // 2-byte UTF-8: [110x xxxx] [10xx xxxx]
+ {true, true, "\xDB\xA5"}, // [1101 1011] [1010 0101] =
+ // Arabic small waw U+06E5
+ {false, false, "\x9B\xA5"}, // [1<0>01 1011] [1010 0101]
+ {false, false, "\xDB\x25"}, // [1101 1011] [<0>010 0101]
+ {false, false, "\xDB\xE5"}, // [1101 1011] [1<1>10 0101]
+ {true, false, "\xCC\x81"}, // [1100 1100] [1000 0001] =
+ // combining char U+0301
+ {false, false, "\x8C\x81"}, // [1<0>00 1100] [1000 0001]
+ {false, false, "\xCC\x01"}, // [1100 1100] [<0>000 0001]
+ {false, false, "\xCC\xC1"}, // [1100 1100] [1<1>00 0001]
+
+ // 3-byte UTF-8: [1110 xxxx] [10xx xxxx] [10xxxxxx]
+ {true, true, "\xE0\xA4\x85"}, // [1110 0000] [1010 0100] [1000 0101] =
+ // Devanagari Letter A U+0905
+ {false, false, "\xA0\xA4\x85"}, // [1<0>10 0000] [1010 0100] [1000 0101]
+ {false, false, "\xE0\x24\x85"}, // [1110 0000] [<0>010 0100] [1000 0101]
+ {false, false, "\xE0\xE4\x85"}, // [1110 0000] [1<1>10 0100] [1000 0101]
+ {false, false, "\xE0\xA4\x05"}, // [1110 0000] [1010 0100] [<0>000 0101]
+ {false, false, "\xE0\xA4\xC5"}, // [1110 0000] [1010 0100] [1<1>00 0101]
+ {true, false, "\xE0\xA4\x81"}, // [1110 0000] [1010 0100] [1000 0001] =
+ // combining char U+0901
+ {false, false, "\xA0\xA4\x81"}, // [1<0>10 0000] [1010 0100] [1000 0001]
+ {false, false, "\xE0\x24\x81"}, // [1110 0000] [<0>010 0100] [1000 0001]
+ {false, false, "\xE0\xE4\x81"}, // [1110 0000] [1<1>10 0100] [1000 0001]
+ {false, false, "\xE0\xA4\x01"}, // [1110 0000] [1010 0100] [<0>000 0001]
+ {false, false, "\xE0\xA4\xC1"}, // [1110 0000] [1010 0100] [1<1>00 0001]
+ };
+ const bool atNameStart[] = {true, false};
+
+ size_t i = 0;
+ char doc[1024];
+ size_t failCount = 0;
+
+ for (; i < sizeof(cases) / sizeof(cases[0]); i++) {
+ size_t j = 0;
+ for (; j < sizeof(atNameStart) / sizeof(atNameStart[0]); j++) {
+ const bool expectedSuccess
+ = atNameStart[j] ? cases[i].goodNameStart : cases[i].goodName;
+ sprintf(doc, "<%s%s><!--", atNameStart[j] ? "" : "a", cases[i].tagName);
+ XML_Parser parser = XML_ParserCreate(NULL);
+
+ const enum XML_Status status
+ = XML_Parse(parser, doc, (int)strlen(doc), /*isFinal=*/XML_FALSE);
+
+ bool success = true;
+ if ((status == XML_STATUS_OK) != expectedSuccess) {
+ success = false;
+ }
+ if ((status == XML_STATUS_ERROR)
+ && (XML_GetErrorCode(parser) != XML_ERROR_INVALID_TOKEN)) {
+ success = false;
+ }
+
+ if (! success) {
+ fprintf(
+ stderr,
+ "FAIL case %2u (%sat name start, %u-byte sequence, error code %d)\n",
+ (unsigned)i + 1u, atNameStart[j] ? " " : "not ",
+ (unsigned)strlen(cases[i].tagName), XML_GetErrorCode(parser));
+ failCount++;
+ }
+
+ XML_ParserFree(parser);
+ }
+ }
+
+ if (failCount > 0) {
+ fail("UTF-8 regression detected");
+ }
+}
+END_TEST
+
/* Test trailing spaces in elements are accepted */
static void XMLCALL
record_element_end_handler(void *userData, const XML_Char *name) {
@@ -6175,6 +6274,14 @@ START_TEST(test_bad_doctype) {
}
END_TEST
+START_TEST(test_bad_doctype_utf8) {
+ const char *text = "<!DOCTYPE \xDB\x25"
+ "doc><doc/>"; // [1101 1011] [<0>010 0101]
+ expect_failure(text, XML_ERROR_INVALID_TOKEN,
+ "Invalid UTF-8 in DOCTYPE not faulted");
+}
+END_TEST
+
START_TEST(test_bad_doctype_utf16) {
const char text[] =
/* <!DOCTYPE doc [ \x06f2 ]><doc/>
@@ -11870,6 +11977,7 @@ make_suite(void) {
tcase_add_test(tc_basic, test_ext_entity_utf8_non_bom);
tcase_add_test(tc_basic, test_utf8_in_cdata_section);
tcase_add_test(tc_basic, test_utf8_in_cdata_section_2);
+ tcase_add_test(tc_basic, test_utf8_in_start_tags);
tcase_add_test(tc_basic, test_trailing_spaces_in_elements);
tcase_add_test(tc_basic, test_utf16_attribute);
tcase_add_test(tc_basic, test_utf16_second_attr);
@@ -11878,6 +11986,7 @@ make_suite(void) {
tcase_add_test(tc_basic, test_bad_attr_desc_keyword);
tcase_add_test(tc_basic, test_bad_attr_desc_keyword_utf16);
tcase_add_test(tc_basic, test_bad_doctype);
+ tcase_add_test(tc_basic, test_bad_doctype_utf8);
tcase_add_test(tc_basic, test_bad_doctype_utf16);
tcase_add_test(tc_basic, test_bad_doctype_plus);
tcase_add_test(tc_basic, test_bad_doctype_star);