Forbid direct instantiation of iterator types#1377
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type(iter(md.keys())).__new__(t) built an uninitialised iterator whose md pointer was NULL; calling next() on it dereferenced NULL and segfaulted. The view types were given a forbidden tp_new in aio-libs#1163 for the same reason (aio-libs#1161); the iterator types share the hole. Add the same forbidden tp_new to the items/keys/values iterator specs. Adds a C-extension regression test mirroring the view one.
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What do these changes do?
type(iter(md.keys())).__new__(t)built an uninitialised iterator whose internalmdpointer was NULL;calling
next()on it dereferenced NULL and segfaulted. The view types were given a forbiddentp_newfor exactly this reason in #1163; the iterator types share the hole. This adds the same forbidden
tp_newto the items/keys/values iterator specs. This is a C-extension-only concern (the pure-Pythoniterators are ordinary Python objects); no pure-Python change is needed.
Are there changes in behavior for the user?
Yes: directly constructing an internal iterator type now raises
TypeError: cannot create '..._keysiter' instances directlyinstead of crashing. Normal iteration isunaffected.
Is it a substantial burden for the maintainers to support this?
No. It mirrors the existing view-type fix (#1163).
Related issue number
Direct analog of #1163 (view types); same crash class as #1161. Surfaced by the analysis report #1306.
Checklist
test_iter_direct_instantiation_segfault)CONTRIBUTORS.txtin this repoCHANGES/folder