Skip to content

gh-151126: Check strdup result in readline on_completion #156299

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
KowalskiThomas wants to merge 1 commit into from
Closed

gh-151126: Check strdup result in readline on_completion #156299

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-08-23-16-36-00.gh-issue-151126.m3YbXU.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Raise :exc:`MemoryError` on allocation failure in the :mod:`!readline`
completion callback.
4 changes: 4 additions & 0 deletions Modules/readline.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1272,6 +1272,10 @@ on_completion(const char *text, int state)
goto error;
result = strdup(PyBytes_AS_STRING(encoded));

@cmaloney cmaloney Oct 21, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think this should actually change to _PyMem_Strdup while we're here

@KowalskiThomas KowalskiThomas Oct 21, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Will do depending on whether we just close the PR or not!

Py_DECREF(encoded);
if (result == NULL) {
PyErr_NoMemory();

@cmaloney cmaloney Oct 21, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I don't think this works right as the goto err will clear the memory error set

@KowalskiThomas KowalskiThomas Oct 21, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

🤔 You're right, indeed.

Looking a bit more at it, I'm starting to wonder if the lack of checking strdup result is an oversight or on purpose, since the function ignores all errors that can happen and doesn't seem to ever return / raise them.

So I'm not quite sure what I should do here. It seems like actually bubbling the exception all the way up to input would require "setting the exception" somewhere, so that the actual "reading loop" can detect it and abort/actually raise the exception.

Alternatively, it might make sense to just explicitly ignore the result of strdup (since at this point it's likely the user impact is none or near none), and if strdup it's also likely things will blow up not much later...

goto error;
}
}
Py_DECREF(r);
goto done;
Expand Down
Loading