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Issue #24848: Fixed bugs in UTF-7 decoding of misformed data: 

1. Non-ASCII bytes were accepted after shift sequence.
2. A low surrogate could be emitted in case of error in high surrogate.
This commit is contained in:
Serhiy Storchaka 2015-10-02 13:07:28 +03:00
parent 223349cfb8
commit 28b21e50c8
4 changed files with 75 additions and 11 deletions
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60
Lib/test/test_codecs.py
View File

@ -898,6 +898,32 @@ class CP65001Test(ReadTest, unittest.TestCase):
class UTF7Test(ReadTest, unittest.TestCase):
encoding = "utf-7"
def test_ascii(self):
# Set D (directly encoded characters)
set_d = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
'abcdefghijklmnopqrstuvwxyz'
'0123456789'
'\'(),-./:?')
self.assertEqual(set_d.encode(self.encoding), set_d.encode('ascii'))
self.assertEqual(set_d.encode('ascii').decode(self.encoding), set_d)
# Set O (optional direct characters)
set_o = ' !"#$%&*;<=>@[]^_`{|}'
self.assertEqual(set_o.encode(self.encoding), set_o.encode('ascii'))
self.assertEqual(set_o.encode('ascii').decode(self.encoding), set_o)
# +
self.assertEqual('a+b'.encode(self.encoding), b'a+-b')
self.assertEqual(b'a+-b'.decode(self.encoding), 'a+b')
# White spaces
ws = ' \t\n\r'
self.assertEqual(ws.encode(self.encoding), ws.encode('ascii'))
self.assertEqual(ws.encode('ascii').decode(self.encoding), ws)
# Other ASCII characters
other_ascii = ''.join(sorted(set(bytes(range(0x80)).decode()) -
set(set_d + set_o + '+' + ws)))
self.assertEqual(other_ascii.encode(self.encoding),
b'+AAAAAQACAAMABAAFAAYABwAIAAsADAAOAA8AEAARABIAEwAU'
b'ABUAFgAXABgAGQAaABsAHAAdAB4AHwBcAH4Afw-')
def test_partial(self):
self.check_partial(
'a+-b\x00c\x80d\u0100e\U00010000f',
@ -939,7 +965,9 @@ class UTF7Test(ReadTest, unittest.TestCase):
def test_errors(self):
tests = [
(b'\xffb', '\ufffdb'),
(b'a\xffb', 'a\ufffdb'),
(b'a\xff\xffb', 'a\ufffd\ufffdb'),
(b'a+IK', 'a\ufffd'),
(b'a+IK-b', 'a\ufffdb'),
(b'a+IK,b', 'a\ufffdb'),
@ -955,6 +983,8 @@ class UTF7Test(ReadTest, unittest.TestCase):
(b'a+//,+IKw-b', 'a\ufffd\u20acb'),
(b'a+///,+IKw-b', 'a\uffff\ufffd\u20acb'),
(b'a+////,+IKw-b', 'a\uffff\ufffd\u20acb'),
(b'a+IKw-b\xff', 'a\u20acb\ufffd'),
(b'a+IKw\xffb', 'a\u20ac\ufffdb'),
]
for raw, expected in tests:
with self.subTest(raw=raw):
@ -966,8 +996,36 @@ class UTF7Test(ReadTest, unittest.TestCase):
self.assertEqual('\U000104A0'.encode(self.encoding), b'+2AHcoA-')
self.assertEqual('\ud801\udca0'.encode(self.encoding), b'+2AHcoA-')
self.assertEqual(b'+2AHcoA-'.decode(self.encoding), '\U000104A0')
self.assertEqual(b'+2AHcoA'.decode(self.encoding), '\U000104A0')
self.assertEqual('\u20ac\U000104A0'.encode(self.encoding), b'+IKzYAdyg-')
self.assertEqual(b'+IKzYAdyg-'.decode(self.encoding), '\u20ac\U000104A0')
self.assertEqual(b'+IKzYAdyg'.decode(self.encoding), '\u20ac\U000104A0')
self.assertEqual('\u20ac\u20ac\U000104A0'.encode(self.encoding),
b'+IKwgrNgB3KA-')
self.assertEqual(b'+IKwgrNgB3KA-'.decode(self.encoding),
'\u20ac\u20ac\U000104A0')
self.assertEqual(b'+IKwgrNgB3KA'.decode(self.encoding),
'\u20ac\u20ac\U000104A0')
test_lone_surrogates = None
def test_lone_surrogates(self):
tests = [
(b'a+2AE-b', 'a\ud801b'),
(b'a+2AE\xffb', 'a\ufffdb'),
(b'a+2AE', 'a\ufffd'),
(b'a+2AEA-b', 'a\ufffdb'),
(b'a+2AH-b', 'a\ufffdb'),
(b'a+IKzYAQ-b', 'a\u20ac\ud801b'),
(b'a+IKzYAQ\xffb', 'a\u20ac\ufffdb'),
(b'a+IKzYAQA-b', 'a\u20ac\ufffdb'),
(b'a+IKzYAd-b', 'a\u20ac\ufffdb'),
(b'a+IKwgrNgB-b', 'a\u20ac\u20ac\ud801b'),
(b'a+IKwgrNgB\xffb', 'a\u20ac\u20ac\ufffdb'),
(b'a+IKwgrNgB', 'a\u20ac\u20ac\ufffd'),
(b'a+IKwgrNgBA-b', 'a\u20ac\u20ac\ufffdb'),
]
for raw, expected in tests:
with self.subTest(raw=raw):
self.assertEqual(raw.decode('utf-7', 'replace'), expected)
class UTF16ExTest(unittest.TestCase):

3
Lib/test/test_unicode.py
View File

@ -1524,7 +1524,7 @@ class UnicodeTest(string_tests.CommonTest,
self.assertEqual(b'+2AHab9ze-'.decode('utf-7'), '\uD801\U000abcde')
# Issue #2242: crash on some Windows/MSVC versions
self.assertEqual(b'+\xc1'.decode('utf-7'), '\xc1')
self.assertEqual(b'+\xc1'.decode('utf-7', 'ignore'), '')
# Direct encoded characters
set_d = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'(),-./:?"
@ -1966,6 +1966,7 @@ class UnicodeTest(string_tests.CommonTest,
self.assertRaises(UnicodeError, str, b'Andr\202 x', 'ascii', 'strict')
self.assertEqual(str(b'Andr\202 x', 'ascii', 'ignore'), "Andr x")
self.assertEqual(str(b'Andr\202 x', 'ascii', 'replace'), 'Andr\uFFFD x')
self.assertEqual(str(b'\202 x', 'ascii', 'replace'), '\uFFFD x')
# Error handling (unknown character names)
self.assertEqual(b"\\N{foo}xx".decode("unicode-escape", "ignore"), "xx")

2
Misc/NEWS
View File

@ -10,6 +10,8 @@ Release date: tba
Core and Builtins
-----------------
- Issue #24848: Fixed a number of bugs in UTF-7 decoding of misformed data.
- Issue #25280: Import trace messages emitted in verbose (-v) mode are no
longer formatted twice.

21
Objects/unicodeobject.c
View File

@ -4381,31 +4381,31 @@ PyUnicode_DecodeUTF7Stateful(const char *s,
}
else { /* now leaving a base-64 section */
inShift = 0;
s++;
if (surrogate) {
if (_PyUnicodeWriter_WriteCharInline(&writer, surrogate) < 0)
goto onError;
surrogate = 0;
}
if (base64bits > 0) { /* left-over bits */
if (base64bits >= 6) {
/* We've seen at least one base-64 character */
s++;
errmsg = "partial character in shift sequence";
goto utf7Error;
}
else {
/* Some bits remain; they should be zero */
if (base64buffer != 0) {
s++;
errmsg = "non-zero padding bits in shift sequence";
goto utf7Error;
}
}
}
if (ch != '-') {
if (surrogate && DECODE_DIRECT(ch)) {
if (_PyUnicodeWriter_WriteCharInline(&writer, surrogate) < 0)
goto onError;
}
surrogate = 0;
if (ch == '-') {
/* '-' is absorbed; other terminating
characters are preserved */
if (_PyUnicodeWriter_WriteCharInline(&writer, ch) < 0)
goto onError;
s++;
}
}
}
@ -4419,6 +4419,7 @@ PyUnicode_DecodeUTF7Stateful(const char *s,
}
else { /* begin base64-encoded section */
inShift = 1;
surrogate = 0;
shiftOutStart = writer.pos;
base64bits = 0;
base64buffer = 0;
@ -4450,6 +4451,7 @@ utf7Error:
if (inShift && !consumed) { /* in shift sequence, no more to follow */
/* if we're in an inconsistent state, that's an error */
inShift = 0;
if (surrogate ||
(base64bits >= 6) ||
(base64bits > 0 && base64buffer != 0)) {
@ -13337,6 +13339,7 @@ _PyUnicodeWriter_PrepareInternal(_PyUnicodeWriter *writer,
if (maxchar > writer->maxchar || writer->readonly) {
/* resize + widen */
maxchar = Py_MAX(maxchar, writer->maxchar);
newbuffer = PyUnicode_New(newlen, maxchar);
if (newbuffer == NULL)
return -1;