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Issue #1621: Fix undefined behaviour from signed overflow in datetime module hashes, array and list iterations, and get_integer (stringlib/string_format.h)

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This commit is contained in:
Mark Dickinson 2011-09-25 15:34:32 +01:00
parent 50203a69b3
commit c7d93b7614
4 changed files with 14 additions and 16 deletions
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6
Objects/listobject.c
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@ -2434,7 +2434,7 @@ list_subscript(PyListObject* self, PyObject* item)
src = self->ob_item;
dest = ((PyListObject *)result)->ob_item;
for (cur = start, i = 0; i < slicelength;
cur += step, i++) {
cur += (size_t)step, i++) {
it = src[cur];
Py_INCREF(it);
dest[i] = it;
@ -2525,7 +2525,7 @@ list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value)
self->ob_item + cur + 1,
lim * sizeof(PyObject *));
}
cur = start + slicelength*step;
cur = start + (size_t)slicelength * step;
if (cur < (size_t)Py_SIZE(self)) {
memmove(self->ob_item + cur - slicelength,
self->ob_item + cur,
@ -2589,7 +2589,7 @@ list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value)
selfitems = self->ob_item;
seqitems = PySequence_Fast_ITEMS(seq);
for (cur = start, i = 0; i < slicelength;
cur += step, i++) {
cur += (size_t)step, i++) {
garbage[i] = selfitems[cur];
ins = seqitems[i];
Py_INCREF(ins);

14
Objects/stringlib/string_format.h
View file

@ -209,19 +209,17 @@ get_integer(const SubString *str)
if (digitval < 0)
return -1;
/*
This trick was copied from old Unicode format code. It's cute,
but would really suck on an old machine with a slow divide
implementation. Fortunately, in the normal case we do not
expect too many digits.
Detect possible overflow before it happens:
accumulator * 10 + digitval > PY_SSIZE_T_MAX if and only if
accumulator > (PY_SSIZE_T_MAX - digitval) / 10.
*/
oldaccumulator = accumulator;
accumulator *= 10;
if ((accumulator+10)/10 != oldaccumulator+1) {
if (accumulator > (PY_SSIZE_T_MAX - digitval) / 10) {
PyErr_Format(PyExc_ValueError,
"Too many decimal digits in format string");
return -1;
}
accumulator += digitval;
accumulator = accumulator * 10 + digitval;
}
return accumulator;
}