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Be stricter about macro XML_CONTEXT_BYTES

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- Start treating -DXML_CONTEXT_BYTES=0 as "no context"
  rather than "context of size 0".  Was documented as
  "must be set to a positive integer", previously.

- Enforce that macro XML_CONTEXT_BYTES is defined at build time to
  avoid accidental misbuilds lacking context in environments that
  bypass both of Expats official build systems.

- Detect and reject use of negative context size at compile time.
This commit is contained in:
Sebastian Pipping 2023-10-04 16:21:27 +02:00
parent acbcd0915d
commit 23110a864d
9 changed files with 38 additions and 29 deletions
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2
.github/workflows/linux.yml vendored
View file

@ -56,7 +56,7 @@ jobs:
- MODE: qa-sh
FLAT_ENV: CC=clang CXX=clang++ LD=clang++ QA_SANITIZER=address CMAKE_ARGS=-DEXPAT_ATTR_INFO=ON
- MODE: qa-sh
FLAT_ENV: CC=clang CXX=clang++ LD=clang++ QA_SANITIZER=address CMAKE_ARGS=-DEXPAT_CONTEXT_BYTES=OFF
FLAT_ENV: CC=clang CXX=clang++ LD=clang++ QA_SANITIZER=address CMAKE_ARGS=-DEXPAT_CONTEXT_BYTES=0
- MODE: qa-sh
FLAT_ENV: CC=clang CXX=clang++ LD=clang++ QA_SANITIZER=address CMAKE_ARGS=-DEXPAT_DTD=OFF
- MODE: qa-sh

5
expat/CMakeLists.txt
View file

@ -139,7 +139,7 @@ if(UNIX OR _EXPAT_HELP)
expat_shy_set(EXPAT_WITH_LIBBSD OFF CACHE BOOL "Utilize libbsd (for arc4random_buf)")
endif()
expat_shy_set(EXPAT_ENABLE_INSTALL ON CACHE BOOL "Install expat files in cmake install target")
expat_shy_set(EXPAT_CONTEXT_BYTES 1024 CACHE STRING "Define to specify how much context to retain around the current parse point")
expat_shy_set(EXPAT_CONTEXT_BYTES 1024 CACHE STRING "Define to specify how much context to retain around the current parse point, 0 to disable")
mark_as_advanced(EXPAT_CONTEXT_BYTES)
expat_shy_set(EXPAT_DTD ON CACHE BOOL "Define to make parameter entity parsing functionality available")
mark_as_advanced(EXPAT_DTD)
@ -287,6 +287,9 @@ _expat_copy_bool_int(EXPAT_NS XML_NS)
if(NOT WIN32)
_expat_copy_bool_int(EXPAT_DEV_URANDOM XML_DEV_URANDOM)
endif()
if(NOT EXPAT_CONTEXT_BYTES GREATER 0) # in particular with -DEXPAT_CONTEXT_BYTES=OFF
set(EXPAT_CONTEXT_BYTES 0)
endif()
set(XML_CONTEXT_BYTES ${EXPAT_CONTEXT_BYTES})
macro(expat_install)

7
expat/configure.ac
View file

@ -327,9 +327,10 @@ AS_HELP_STRING([--disable-xml-context],
AS_IF([test "x${enable_xml_context}" != "xno"],
[AS_IF([test "x${enable_xml_context}" = "xyes" \
-o "x${enable_xml_context}" = "x"],
[AS_VAR_SET(enable_xml_context,1024)])
AC_DEFINE_UNQUOTED([XML_CONTEXT_BYTES], [${enable_xml_context}],
[Define to specify how much context to retain around the current parse point.])])
[AS_VAR_SET(enable_xml_context,1024)])],
[AS_VAR_SET(enable_xml_context,0)])
AC_DEFINE_UNQUOTED([XML_CONTEXT_BYTES], [${enable_xml_context}],
[Define to specify how much context to retain around the current parse point, 0 to disable.])
AC_ARG_WITH([docbook],
[AS_HELP_STRING([--with-docbook],

6
expat/doc/reference.html
View file

@ -404,8 +404,8 @@ off by default.</dd>
<dd>The number of input bytes of markup context which the parser will
ensure are available for reporting via <code><a href=
"#XML_GetInputContext" >XML_GetInputContext</a></code>. This is
normally set to 1024, and must be set to a positive integer. If this
is not defined, the input context will not be available and <code><a
normally set to 1024, and must be set to a positive integer to enable.
If this is set to zero, the input context will not be available and <code><a
href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will
always report <code>NULL</code>. Without this, Expat has a smaller memory
footprint and can be faster.</dd>
@ -2136,7 +2136,7 @@ untranslated bytes of the input.</p>
triggering a call spans over a very large amount of input, the actual
parse position may be before the beginning of the buffer.</p>
<p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always
<p>If <code>XML_CONTEXT_BYTES</code> is zero, this will always
return <code>NULL</code>.</p>
</div>

4
expat/expat_config.h.cmake
View file

@ -94,8 +94,8 @@
#cmakedefine XML_ATTR_INFO
/* Define to specify how much context to retain around the current parse
point. */
#cmakedefine XML_CONTEXT_BYTES @XML_CONTEXT_BYTES@
point, 0 to disable. */
#define XML_CONTEXT_BYTES @XML_CONTEXT_BYTES@
#if ! defined(_WIN32)
/* Define to include code reading entropy from `/dev/urandom'. */

2
expat/lib/expat.h
View file

@ -951,7 +951,7 @@ XMLPARSEAPI(XML_Index) XML_GetCurrentByteIndex(XML_Parser parser);
XMLPARSEAPI(int)
XML_GetCurrentByteCount(XML_Parser parser);
/* If XML_CONTEXT_BYTES is defined, returns the input buffer, sets
/* If XML_CONTEXT_BYTES is >=1, returns the input buffer, sets
the integer pointed to by offset to the offset within this buffer
of the current parse position, and sets the integer pointed to by size
to the size of this buffer (the number of input bytes). Otherwise

31
expat/lib/xmlparse.c
View file

@ -63,6 +63,11 @@
#include "expat_config.h"
#if ! defined(XML_CONTEXT_BYTES) || (1 - XML_CONTEXT_BYTES - 1 == 2) \
|| (XML_CONTEXT_BYTES + 0 < 0)
# error XML_CONTEXT_BYTES must be defined, non-empty and >=0 (0 to disable, >=1 to enable; 1024 is a common default)
#endif
#if defined(HAVE_SYSCALL_GETRANDOM)
# if ! defined(_GNU_SOURCE)
# define _GNU_SOURCE 1 /* syscall prototype */
@ -1905,7 +1910,7 @@ XML_Parse(XML_Parser parser, const char *s, int len, int isFinal) {
parser->m_processor = errorProcessor;
return XML_STATUS_ERROR;
}
#ifndef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES == 0
else if (parser->m_bufferPtr == parser->m_bufferEnd) {
const char *end;
int nLeftOver;
@ -1976,7 +1981,7 @@ XML_Parse(XML_Parser parser, const char *s, int len, int isFinal) {
parser->m_eventEndPtr = parser->m_bufferPtr;
return result;
}
#endif /* not defined XML_CONTEXT_BYTES */
#endif /* XML_CONTEXT_BYTES == 0 */
else {
void *buff = XML_GetBuffer(parser, len);
if (buff == NULL)
@ -2072,9 +2077,9 @@ XML_GetBuffer(XML_Parser parser, int len) {
}
if (len > EXPAT_SAFE_PTR_DIFF(parser->m_bufferLim, parser->m_bufferEnd)) {
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
int keep;
#endif /* defined XML_CONTEXT_BYTES */
#endif /* XML_CONTEXT_BYTES > 0 */
/* Do not invoke signed arithmetic overflow: */
int neededSize = (int)((unsigned)len
+ (unsigned)EXPAT_SAFE_PTR_DIFF(
@ -2083,7 +2088,7 @@ XML_GetBuffer(XML_Parser parser, int len) {
parser->m_errorCode = XML_ERROR_NO_MEMORY;
return NULL;
}
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
keep = (int)EXPAT_SAFE_PTR_DIFF(parser->m_bufferPtr, parser->m_buffer);
if (keep > XML_CONTEXT_BYTES)
keep = XML_CONTEXT_BYTES;
@ -2093,10 +2098,10 @@ XML_GetBuffer(XML_Parser parser, int len) {
return NULL;
}
neededSize += keep;
#endif /* defined XML_CONTEXT_BYTES */
#endif /* XML_CONTEXT_BYTES > 0 */
if (neededSize
<= EXPAT_SAFE_PTR_DIFF(parser->m_bufferLim, parser->m_buffer)) {
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
if (keep < EXPAT_SAFE_PTR_DIFF(parser->m_bufferPtr, parser->m_buffer)) {
int offset
= (int)EXPAT_SAFE_PTR_DIFF(parser->m_bufferPtr, parser->m_buffer)
@ -2117,7 +2122,7 @@ XML_GetBuffer(XML_Parser parser, int len) {
+ EXPAT_SAFE_PTR_DIFF(parser->m_bufferEnd, parser->m_bufferPtr);
parser->m_bufferPtr = parser->m_buffer;
}
#endif /* not defined XML_CONTEXT_BYTES */
#endif /* XML_CONTEXT_BYTES > 0 */
} else {
char *newBuf;
int bufferSize
@ -2138,7 +2143,7 @@ XML_GetBuffer(XML_Parser parser, int len) {
return NULL;
}
parser->m_bufferLim = newBuf + bufferSize;
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
if (parser->m_bufferPtr) {
memcpy(newBuf, &parser->m_bufferPtr[-keep],
EXPAT_SAFE_PTR_DIFF(parser->m_bufferEnd, parser->m_bufferPtr)
@ -2168,7 +2173,7 @@ XML_GetBuffer(XML_Parser parser, int len) {
parser->m_bufferEnd = newBuf;
}
parser->m_bufferPtr = parser->m_buffer = newBuf;
#endif /* not defined XML_CONTEXT_BYTES */
#endif /* XML_CONTEXT_BYTES > 0 */
}
parser->m_eventPtr = parser->m_eventEndPtr = NULL;
parser->m_positionPtr = NULL;
@ -2282,7 +2287,7 @@ XML_GetCurrentByteCount(XML_Parser parser) {
const char *XMLCALL
XML_GetInputContext(XML_Parser parser, int *offset, int *size) {
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
if (parser == NULL)
return NULL;
if (parser->m_eventPtr && parser->m_buffer) {
@ -2296,7 +2301,7 @@ XML_GetInputContext(XML_Parser parser, int *offset, int *size) {
(void)parser;
(void)offset;
(void)size;
#endif /* defined XML_CONTEXT_BYTES */
#endif /* XML_CONTEXT_BYTES > 0 */
return (const char *)0;
}
@ -2516,7 +2521,7 @@ XML_GetFeatureList(void) {
#ifdef XML_DTD
{XML_FEATURE_DTD, XML_L("XML_DTD"), 0},
#endif
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
{XML_FEATURE_CONTEXT_BYTES, XML_L("XML_CONTEXT_BYTES"),
XML_CONTEXT_BYTES},
#endif

8
expat/tests/basic_tests.c
View file

@ -2796,7 +2796,7 @@ START_TEST(test_get_buffer_1) {
* between INT_MAX and INT_MAX/2. A gap of 1K seems comfortable,
* with an extra byte just to ensure that the request is off any
* boundary. The request will be inflated internally by
* XML_CONTEXT_BYTES (if defined), so we subtract that from our
* XML_CONTEXT_BYTES (if >=1), so we subtract that from our
* request.
*/
if (get_feature(XML_FEATURE_CONTEXT_BYTES, &context_bytes) != XML_STATUS_OK)
@ -2832,7 +2832,7 @@ START_TEST(test_get_buffer_2) {
END_TEST
/* Test for signed integer overflow CVE-2022-23852 */
#if defined(XML_CONTEXT_BYTES)
#if XML_CONTEXT_BYTES > 0
START_TEST(test_get_buffer_3_overflow) {
XML_Parser parser = XML_ParserCreate(NULL);
assert(parser != NULL);
@ -2853,7 +2853,7 @@ START_TEST(test_get_buffer_3_overflow) {
XML_ParserFree(parser);
}
END_TEST
#endif // defined(XML_CONTEXT_BYTES)
#endif // XML_CONTEXT_BYTES > 0
/* Test position information macros */
START_TEST(test_byte_info_at_end) {
@ -5239,7 +5239,7 @@ make_basic_test_case(Suite *s) {
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)
#if XML_CONTEXT_BYTES > 0
tcase_add_test(tc_basic, test_get_buffer_3_overflow);
#endif
tcase_add_test(tc_basic, test_byte_info_at_end);

2
expat/tests/handlers.c
View file

@ -1620,7 +1620,7 @@ rsqb_handler(void *userData, const XML_Char *s, int len) {
void XMLCALL
byte_character_handler(void *userData, const XML_Char *s, int len) {
#ifdef XML_CONTEXT_BYTES
#if XML_CONTEXT_BYTES > 0
int offset, size;
const char *buffer;
ByteTestData *data = (ByteTestData *)userData;