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gh-92888: Fix memoryview bad __index__ use after free #92946

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Merged
Fidget-Spinner merged 12 commits into from
Jun 17, 2022
Merged

gh-92888: Fix memoryview bad __index__ use after free #92946

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73ffb29
Fix memoryview bad `__index__` use after free
Fidget-Spinner May 19, 2022
3581de7
📜🤖 Added by blurb_it.
blurb-it[bot] May 19, 2022
43c66d6
stylistic nits
Fidget-Spinner May 19, 2022
18b921f
Merge branch 'fix_memoryview_auf' of https://github.com/Fidget-Spinne…
Fidget-Spinner May 20, 2022
2f3c04f
Fix whitespace
Fidget-Spinner May 21, 2022
a250b02
Use more comprehensive tests by Serhiy
Fidget-Spinner May 23, 2022
c818990
Add more tests by Serhiy
Fidget-Spinner May 23, 2022
42a706c
Fix newline
Fidget-Spinner May 23, 2022
b650764
Fix for tuple index
Fidget-Spinner May 23, 2022
47bd91f
Address review
Fidget-Spinner May 23, 2022
6890713
Address Victor's review
Fidget-Spinner May 29, 2022
d3edf74
re-add ba=None
Fidget-Spinner May 30, 2022
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8 changes: 3 additions & 5 deletions Lib/test/test_memoryview.py
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Original file line number Diff line number Diff line change
Expand Up @@ -546,6 +546,9 @@ def test_pickle(self):
pickle.dumps(m, proto)

def test_use_released_memory(self):
# gh-92888: Previously it was possible to use a memoryview even after
# backing buffer is freed in certain cases. This tests that those
# cases raise an exception.
size = 128
def release():
m.release()
Expand All @@ -564,25 +567,20 @@ def __bool__(self):
release()
return True

ba = None
m = memoryview(bytearray(b'\xff'*size))
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@vstinner vstinner May 23, 2022

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In my PR, I tried to make the code more generic to test more cases: https://github.com/python/cpython/pull/93127/files#diff-d41c6bb40a1e03fea5a20d15c4077413e0ddde65651147922b625b03a66a2f16R399:

        tp = self.rw_type
        b = self.rw_type(self._source)
        view = self._view(b)

with self.assertRaises(ValueError):
m[MyIndex()]
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@vstinner vstinner May 23, 2022

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This test is very long. Can you try to factorize similar code and use loop with subTest(), and put pack operations in one test method and unpack in another test method?

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@serhiy-storchaka serhiy-storchaka May 25, 2022

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Then we will need to duplicate the definitions of internal classes.

The tested code is so different, that it is difficult to use a loop. And I think that the result will be more complicated.


ba = None
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@serhiy-storchaka serhiy-storchaka May 30, 2022

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It is necessary. The old bytearray should be deallocated before creating a new bytearray, so all bytearrays will be allocated at the same place.

m = memoryview(bytearray(b'\xff'*size))
self.assertEqual(list(m[:MyIndex()]), [255] * 4)

ba = None
m = memoryview(bytearray(b'\xff'*size))
self.assertEqual(list(m[MyIndex():8]), [255] * 4)

ba = None
m = memoryview(bytearray(b'\xff'*size)).cast('B', (64, 2))
with self.assertRaisesRegex(ValueError, "operation forbidden"):
m[MyIndex(), 0]

ba = None
m = memoryview(bytearray(b'\xff'*size)).cast('B', (2, 64))
with self.assertRaisesRegex(ValueError, "operation forbidden"):
m[0, MyIndex()]
Expand Down
29 changes: 16 additions & 13 deletions Objects/memoryobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,11 @@ PyTypeObject _PyManagedBuffer_Type = {
return -1; \
}

/* See gh-92888. These macros signal that we need to check the memoryview
again due to possible read after frees. */
#define CHECK_RELEASED_AGAIN(mv) CHECK_RELEASED(mv)
#define CHECK_RELEASED_INT_AGAIN(mv) CHECK_RELEASED_INT(mv)

#define CHECK_LIST_OR_TUPLE(v) \
if (!PyList_Check(v) && !PyTuple_Check(v)) { \
PyErr_SetString(PyExc_TypeError, \
Expand Down Expand Up @@ -383,7 +388,7 @@ copy_rec(const Py_ssize_t *shape, Py_ssize_t ndim, Py_ssize_t itemsize,
static int
copy_single(PyMemoryViewObject *self, const Py_buffer *dest, const Py_buffer *src)
{
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
char *mem = NULL;

assert(dest->ndim == 1);
Expand Down Expand Up @@ -1690,7 +1695,7 @@ unpack_single(PyMemoryViewObject *self, const char *ptr, const char *fmt)
unsigned char uc;
void *p;

CHECK_RELEASED(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_AGAIN(self);

switch (fmt[0]) {

Expand Down Expand Up @@ -1781,15 +1786,13 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
double d;
void *p;

CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */

switch (fmt[0]) {
/* signed integers */
case 'b': case 'h': case 'i': case 'l':
ld = pylong_as_ld(item);
if (ld == -1 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
switch (fmt[0]) {
case 'b':
if (ld < SCHAR_MIN || ld > SCHAR_MAX) goto err_range;
Expand All @@ -1810,7 +1813,7 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
lu = pylong_as_lu(item);
if (lu == (unsigned long)-1 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
switch (fmt[0]) {
case 'B':
if (lu > UCHAR_MAX) goto err_range;
Expand All @@ -1831,14 +1834,14 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
lld = pylong_as_lld(item);
if (lld == -1 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, lld, long long);
break;
case 'Q':
llu = pylong_as_llu(item);
if (llu == (unsigned long long)-1 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, llu, unsigned long long);
break;

Expand All @@ -1847,14 +1850,14 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
zd = pylong_as_zd(item);
if (zd == -1 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, zd, Py_ssize_t);
break;
case 'N':
zu = pylong_as_zu(item);
if (zu == (size_t)-1 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, zu, size_t);
break;

Expand All @@ -1863,7 +1866,7 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
d = PyFloat_AsDouble(item);
if (d == -1.0 && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
if (fmt[0] == 'f') {
PACK_SINGLE(ptr, d, float);
}
Expand All @@ -1877,7 +1880,7 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
ld = PyObject_IsTrue(item);
if (ld < 0)
return -1; /* preserve original error */
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, ld, _Bool);
break;

Expand All @@ -1895,7 +1898,7 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
p = PyLong_AsVoidPtr(item);
if (p == NULL && PyErr_Occurred())
goto err_occurred;
CHECK_RELEASED_INT(self); /* See gh-92888 for why we need this here */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, p, void *);
break;

Expand Down