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bpo-40120: Fix unbounded struct char[] undefined behavior. #19232

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gpshead wants to merge 5 commits into from
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bpo-40120: Fix unbounded struct char[] undefined behavior. #19232

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809f263
Fix undefined behavior in PyBytesObject.
gpshead Mar 30, 2020
d3329fe
Fix unicode's struct encoding_map similarly.
gpshead Mar 30, 2020
a1759d9
Describe the + 1 used in PyBytesObject_SIZE.
gpshead Mar 30, 2020
630a26a
news!
gpshead Mar 30, 2020
cd483f6
Fix test_sys, it encoded the struct definition.
gpshead Mar 30, 2020
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Fix unicode's struct encoding_map similarly.
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@gpshead
gpshead committed Mar 30, 2020
commit d3329fe0c707a615a8d01507a9d9d0c75b6481a4
6 changes: 3 additions & 3 deletions Objects/unicodeobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8208,14 +8208,14 @@ struct encoding_map {
PyObject_HEAD
unsigned char level1[32];
int count2, count3;
unsigned char level23[1];
unsigned char level23[];

@vstinner vstinner Jan 21, 2022

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@gpshead: Can you please write a PR which only contains this change? Since it doesn't touch the public C API, C++ compatibility is not an issue (I don't think that Python can be built with a C++ compiler). We can start with this change and see how it goes? See also the discussion at python/peps#1349

};

static PyObject*
encoding_map_size(PyObject *obj, PyObject* args)
{
struct encoding_map *map = (struct encoding_map*)obj;
return PyLong_FromLong(sizeof(*map) - 1 + 16*map->count2 +
return PyLong_FromLong(sizeof(*map) + 16*map->count2 +
128*map->count3);
}

Expand Down Expand Up @@ -8347,7 +8347,7 @@ PyUnicode_BuildEncodingMap(PyObject* string)

/* Create a three-level trie */
result = PyObject_MALLOC(sizeof(struct encoding_map) +
16*count2 + 128*count3 - 1);
16*count2 + 128*count3);
if (!result)
return PyErr_NoMemory();
PyObject_Init(result, &EncodingMapType);
Expand Down