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bpo-34395: Don't free allocated memory on realloc fail in load_mark() in _pickle.c. #8788

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Merged
serhiy-storchaka merged 3 commits into from
Aug 25, 2018
Merged

bpo-34395: Don't free allocated memory on realloc fail in load_mark() in _pickle.c. #8788

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bpo-34395: Don't free allocated memory on realloc fail in load_mark()…
sir-sigurd Aug 16, 2018
4f52c1e
Remove unneeded overflow checks.
sir-sigurd Aug 25, 2018
2c99af7
Merge branch 'master' into bpo-34395
sir-sigurd Aug 25, 2018
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9 changes: 4 additions & 5 deletions Modules/_pickle.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6297,14 +6297,13 @@ load_mark(UnpicklerObject *self)
return -1;
}

@serhiy-storchaka serhiy-storchaka Aug 16, 2018 •
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Seems the check above can be removed. alloc > (PY_SSIZE_T_MAX / sizeof(Py_ssize_t)) is duplicated in PyMem_RESIZE(), and failing alloc <= ((size_t)self->num_marks + 1) is not possible if sizeof(Py_ssize_t) > 2.

@sir-sigurd sir-sigurd Aug 16, 2018

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cpython/Modules/_pickle.c

Line 6289 in 1590c39

if ((self->num_marks + 1) >= self->marks_size) {

Also, it seems that new space is needed only when self->num_marks + 1 is strictly greater than self->marks_size.

@serhiy-storchaka serhiy-storchaka Aug 17, 2018

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Agree. This condition can be written as self->num_marks >= self->marks_size or self->num_marks == self->marks_size.

@sir-sigurd sir-sigurd Aug 22, 2018

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@serhiy-storchaka
I'd prefer to make these change as separate commits/RPs as they are not related to this bpo issue.

@sir-sigurd sir-sigurd Aug 22, 2018

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PR for upsizing issue #8860.


Py_ssize_t *marks_old = self->marks;
PyMem_RESIZE(self->marks, Py_ssize_t, alloc);
if (self->marks == NULL) {
PyMem_FREE(marks_old);
self->marks_size = 0;
Py_ssize_t *marks_new = self->marks;
PyMem_RESIZE(marks_new, Py_ssize_t, alloc);
if (marks_new == NULL) {
PyErr_NoMemory();
return -1;
}
self->marks = marks_new;
self->marks_size = (Py_ssize_t)alloc;
}

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