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[3.6] bpo-1621: Avoid signed integer overflow in set_table_resize(). (GH-9059) #9199

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Merged
vstinner merged 1 commit into from
Oct 19, 2018
Merged

[3.6] bpo-1621: Avoid signed integer overflow in set_table_resize(). (GH-9059) #9199

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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2018-09-11-15-19-37.bpo-1621.7o19yG.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Do not assume signed integer overflow behavior (C undefined behavior) when
performing set hash table resizing.
11 changes: 3 additions & 8 deletions Objects/setobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -294,7 +294,6 @@ actually be smaller than the old one.
static int
set_table_resize(PySetObject *so, Py_ssize_t minused)
{
Py_ssize_t newsize;
setentry *oldtable, *newtable, *entry;
Py_ssize_t oldfill = so->fill;
Py_ssize_t oldused = so->used;
Expand All @@ -307,13 +306,9 @@ set_table_resize(PySetObject *so, Py_ssize_t minused)

/* Find the smallest table size > minused. */
/* XXX speed-up with intrinsics */
for (newsize = PySet_MINSIZE;
newsize <= minused && newsize > 0;
newsize <<= 1)
;
if (newsize <= 0) {
PyErr_NoMemory();
return -1;
size_t newsize = PySet_MINSIZE;
while (newsize <= (size_t)minused) {
newsize <<= 1; // The largest possible value is PY_SSIZE_T_MAX + 1.
}

/* Get space for a new table. */
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