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Issue #13612: handle unknown encodings without a buffer overflow.

Browse source 
This affects pyexpat and _elementtree. PyExpat_CAPI now exposes a new
function - DefaultUnknownEncodingHandler.

Based on a patch by Serhiy Storchaka.
This commit is contained in:
Eli Bendersky 2013-05-25 05:25:48 -07:00
parent 6b5a38c728
commit 6dc32b34dd
4 changed files with 128 additions and 79 deletions
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4
Include/pyexpat.h
View file

@ -6,7 +6,7 @@
#define PyExpat_CAPI_MAGIC "pyexpat.expat_CAPI 1.0"
#define PyExpat_CAPSULE_NAME "pyexpat.expat_CAPI"
struct PyExpat_CAPI
struct PyExpat_CAPI
{
char* magic; /* set to PyExpat_CAPI_MAGIC */
int size; /* set to sizeof(struct PyExpat_CAPI) */
@ -46,6 +46,8 @@ struct PyExpat_CAPI
void (*SetStartDoctypeDeclHandler)(XML_Parser parser,
XML_StartDoctypeDeclHandler start);
enum XML_Status (*SetEncoding)(XML_Parser parser, const XML_Char *encoding);
int (*DefaultUnknownEncodingHandler)(
void *encodingHandlerData, const XML_Char *name, XML_Encoding *info);
/* always add new stuff to the end! */
};

92
Lib/test/test_xml_etree.py
View file

@ -690,6 +690,98 @@ def check(encoding, body=''):
check("cp437", '\u221a')
check("mac-roman", '\u02da')
def xml(encoding):
return "<?xml version='1.0' encoding='%s'?><xml />" % encoding
def bxml(encoding):
return xml(encoding).encode(encoding)
supported_encodings = [
'ascii', 'utf-8', 'utf-8-sig', 'utf-16', 'utf-16be', 'utf-16le',
'iso8859-1', 'iso8859-2', 'iso8859-3', 'iso8859-4', 'iso8859-5',
'iso8859-6', 'iso8859-7', 'iso8859-8', 'iso8859-9', 'iso8859-10',
'iso8859-13', 'iso8859-14', 'iso8859-15', 'iso8859-16',
'cp437', 'cp720', 'cp737', 'cp775', 'cp850', 'cp852',
'cp855', 'cp856', 'cp857', 'cp858', 'cp860', 'cp861', 'cp862',
'cp863', 'cp865', 'cp866', 'cp869', 'cp874', 'cp1006', 'cp1250',
'cp1251', 'cp1252', 'cp1253', 'cp1254', 'cp1255', 'cp1256',
'cp1257', 'cp1258',
'mac-cyrillic', 'mac-greek', 'mac-iceland', 'mac-latin2',
'mac-roman', 'mac-turkish',
'iso2022-jp', 'iso2022-jp-1', 'iso2022-jp-2', 'iso2022-jp-2004',
'iso2022-jp-3', 'iso2022-jp-ext',
'koi8-r', 'koi8-u',
'hz', 'ptcp154',
]
for encoding in supported_encodings:
self.assertEqual(ET.tostring(ET.XML(bxml(encoding))), b'<xml />')
unsupported_ascii_compatible_encodings = [
'big5', 'big5hkscs',
'cp932', 'cp949', 'cp950',
'euc-jp', 'euc-jis-2004', 'euc-jisx0213', 'euc-kr',
'gb2312', 'gbk', 'gb18030',
'iso2022-kr', 'johab',
'shift-jis', 'shift-jis-2004', 'shift-jisx0213',
'utf-7',
]
for encoding in unsupported_ascii_compatible_encodings:
self.assertRaises(ValueError, ET.XML, bxml(encoding))
unsupported_ascii_incompatible_encodings = [
'cp037', 'cp424', 'cp500', 'cp864', 'cp875', 'cp1026', 'cp1140',
'utf_32', 'utf_32_be', 'utf_32_le',
]
for encoding in unsupported_ascii_incompatible_encodings:
self.assertRaises(ET.ParseError, ET.XML, bxml(encoding))
self.assertRaises(ValueError, ET.XML, xml('undefined').encode('ascii'))
self.assertRaises(LookupError, ET.XML, xml('xxx').encode('ascii'))
def xml(encoding):
return "<?xml version='1.0' encoding='%s'?><xml />" % encoding
def bxml(encoding):
return xml(encoding).encode(encoding)
supported_encodings = [
'ascii', 'utf-8', 'utf-8-sig', 'utf-16', 'utf-16be', 'utf-16le',
'iso8859-1', 'iso8859-2', 'iso8859-3', 'iso8859-4', 'iso8859-5',
'iso8859-6', 'iso8859-7', 'iso8859-8', 'iso8859-9', 'iso8859-10',
'iso8859-13', 'iso8859-14', 'iso8859-15', 'iso8859-16',
'cp437', 'cp720', 'cp737', 'cp775', 'cp850', 'cp852',
'cp855', 'cp856', 'cp857', 'cp858', 'cp860', 'cp861', 'cp862',
'cp863', 'cp865', 'cp866', 'cp869', 'cp874', 'cp1006', 'cp1250',
'cp1251', 'cp1252', 'cp1253', 'cp1254', 'cp1255', 'cp1256',
'cp1257', 'cp1258',
'mac-cyrillic', 'mac-greek', 'mac-iceland', 'mac-latin2',
'mac-roman', 'mac-turkish',
'iso2022-jp', 'iso2022-jp-1', 'iso2022-jp-2', 'iso2022-jp-2004',
'iso2022-jp-3', 'iso2022-jp-ext',
'koi8-r', 'koi8-u',
'hz', 'ptcp154',
]
for encoding in supported_encodings:
self.assertEqual(ET.tostring(ET.XML(bxml(encoding))), b'<xml />')
unsupported_ascii_compatible_encodings = [
'big5', 'big5hkscs',
'cp932', 'cp949', 'cp950',
'euc-jp', 'euc-jis-2004', 'euc-jisx0213', 'euc-kr',
'gb2312', 'gbk', 'gb18030',
'iso2022-kr', 'johab',
'shift-jis', 'shift-jis-2004', 'shift-jisx0213',
'utf-7',
]
for encoding in unsupported_ascii_compatible_encodings:
self.assertRaises(ValueError, ET.XML, bxml(encoding))
unsupported_ascii_incompatible_encodings = [
'cp037', 'cp424', 'cp500', 'cp864', 'cp875', 'cp1026', 'cp1140',
'utf_32', 'utf_32_be', 'utf_32_le',
]
for encoding in unsupported_ascii_incompatible_encodings:
self.assertRaises(ET.ParseError, ET.XML, bxml(encoding))
self.assertRaises(ValueError, ET.XML, xml('undefined').encode('ascii'))
self.assertRaises(LookupError, ET.XML, xml('xxx').encode('ascii'))
def test_methods(self):
# Test serialization methods.

43
Modules/_elementtree.c
View file

@ -3136,47 +3136,6 @@ expat_pi_handler(XMLParserObject* self, const XML_Char* target_in,
}
}
static int
expat_unknown_encoding_handler(XMLParserObject *self, const XML_Char *name,
XML_Encoding *info)
{
PyObject* u;
unsigned char s[256];
int i;
void *data;
unsigned int kind;
memset(info, 0, sizeof(XML_Encoding));
for (i = 0; i < 256; i++)
s[i] = i;
u = PyUnicode_Decode((char*) s, 256, name, "replace");
if (!u)
return XML_STATUS_ERROR;
if (PyUnicode_READY(u))
return XML_STATUS_ERROR;
if (PyUnicode_GET_LENGTH(u) != 256) {
Py_DECREF(u);
return XML_STATUS_ERROR;
}
kind = PyUnicode_KIND(u);
data = PyUnicode_DATA(u);
for (i = 0; i < 256; i++) {
Py_UCS4 ch = PyUnicode_READ(kind, data, i);
if (ch != Py_UNICODE_REPLACEMENT_CHARACTER)
info->map[i] = ch;
else
info->map[i] = -1;
}
Py_DECREF(u);
return XML_STATUS_OK;
}
/* -------------------------------------------------------------------- */
static PyObject *
@ -3278,7 +3237,7 @@ xmlparser_init(PyObject *self, PyObject *args, PyObject *kwds)
);
EXPAT(SetUnknownEncodingHandler)(
self_xp->parser,
(XML_UnknownEncodingHandler) expat_unknown_encoding_handler, NULL
EXPAT(DefaultUnknownEncodingHandler), NULL
);
return 0;

68
Modules/pyexpat.c
View file

@ -1111,53 +1111,49 @@ static struct PyMethodDef xmlparse_methods[] = {
Make it as simple as possible.
*/
static char template_buffer[257];
static void
init_template_buffer(void)
{
int i;
for (i = 0; i < 256; i++) {
template_buffer[i] = i;
}
template_buffer[256] = 0;
}
static int
PyUnknownEncodingHandler(void *encodingHandlerData,
const XML_Char *name,
XML_Encoding *info)
{
PyUnicodeObject *_u_string = NULL;
int result = 0;
static unsigned char template_buffer[256] = {0};
PyObject* u;
int i;
int kind;
void *data;
unsigned int kind;
/* Yes, supports only 8bit encodings */
_u_string = (PyUnicodeObject *)
PyUnicode_Decode(template_buffer, 256, name, "replace");
if (_u_string == NULL || PyUnicode_READY(_u_string) == -1)
return result;
kind = PyUnicode_KIND(_u_string);
data = PyUnicode_DATA(_u_string);
for (i = 0; i < 256; i++) {
/* Stupid to access directly, but fast */
Py_UCS4 c = PyUnicode_READ(kind, data, i);
if (c == Py_UNICODE_REPLACEMENT_CHARACTER)
info->map[i] = -1;
else
info->map[i] = c;
if (template_buffer[1] == 0) {
for (i = 0; i < 256; i++)
template_buffer[i] = i;
}
u = PyUnicode_Decode((char*) template_buffer, 256, name, "replace");
if (u == NULL || PyUnicode_READY(u))
return XML_STATUS_ERROR;
if (PyUnicode_GET_LENGTH(u) != 256) {
Py_DECREF(u);
PyErr_SetString(PyExc_ValueError,
"multi-byte encodings are not supported");
return XML_STATUS_ERROR;
}
kind = PyUnicode_KIND(u);
data = PyUnicode_DATA(u);
for (i = 0; i < 256; i++) {
Py_UCS4 ch = PyUnicode_READ(kind, data, i);
if (ch != Py_UNICODE_REPLACEMENT_CHARACTER)
info->map[i] = ch;
else
info->map[i] = -1;
}
info->data = NULL;
info->convert = NULL;
info->release = NULL;
result = 1;
Py_DECREF(_u_string);
return result;
Py_DECREF(u);
return XML_STATUS_OK;
}
@ -1752,7 +1748,6 @@ MODULE_INITFUNC(void)
Py_BuildValue("(iii)", info.major,
info.minor, info.micro));
}
init_template_buffer();
/* XXX When Expat supports some way of figuring out how it was
compiled, this should check and set native_encoding
appropriately.
@ -1938,6 +1933,7 @@ MODULE_INITFUNC(void)
capi.SetUserData = XML_SetUserData;
capi.SetStartDoctypeDeclHandler = XML_SetStartDoctypeDeclHandler;
capi.SetEncoding = XML_SetEncoding;
capi.DefaultUnknownEncodingHandler = PyUnknownEncodingHandler;
/* export using capsule */
capi_object = PyCapsule_New(&capi, PyExpat_CAPSULE_NAME, NULL);