Skip to content

gh-156953: Fix a reference leak in curses window.insnstr() - #156954

Merged
serhiy-storchaka merged 1 commit into
python:mainfrom
fedonman:fix-curses-insnstr-bytes-refleak
Sep 7, 2026
Merged

gh-156953: Fix a reference leak in curses window.insnstr()#156954
serhiy-storchaka merged 1 commit into
python:mainfrom
fedonman:fix-curses-insnstr-bytes-refleak

Conversation

@fedonman

@fedonman fedonman commented Sep 4, 2026 •
edited by bedevere-app Bot
Loading

Copy link
Copy Markdown
Contributor

_curses_window_insnstr_impl() frees the wide string when curses_wattr_save() or curses_wattrset() fails, but never decrefs the bytes object PyCurses_ConvertToString() returned as a new reference, so each failing call leaks one reference to the caller's argument. GH-145609 added that decref to addstr(), addnstr() and insstr() and skipped insnstr(); this adds the missing line and a test covering all four.

There is no NEWS entry because no released version can reach the leak: 3.15 has the same omission, but detaching a window arrived with the multi-terminal screen API in GH-151748, so nothing there makes the rendition call fail.

@fedonman
pythongh-156953: Fix a reference leak in curses window.insnstr()
2aa786f 
insnstr() sets the window rendition before the write.  When that fails
it released the wide string but not the bytes object that
PyCurses_ConvertToString() returned as a new reference, so each failing
call leaked one reference to the caller's argument.  addstr(), addnstr()
and insstr() already release it at the same point.
@bedevere-app bedevere-app Bot mentioned this pull request Sep 4, 2026
Closed
serhiy-storchaka
serhiy-storchaka approved these changes Sep 7, 2026
View reviewed changes

@serhiy-storchaka serhiy-storchaka left a comment

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

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

LGTM. 👍

It is worth to backport the fix to 3.15, even if we cannot reproduce the leak there.

@serhiy-storchaka serhiy-storchaka added the needs backport to 3.15 pre-release feature fixes, bugs and security fixes label Sep 7, 2026
@serhiy-storchaka
serhiy-storchaka merged commit 23180c5 into python:main Sep 7, 2026
61 checks passed
@miss-islington-app

miss-islington-app Bot commented Sep 7, 2026

Copy link
Copy Markdown

Thanks @fedonman for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖

@miss-islington-app

miss-islington-app Bot commented Sep 7, 2026

Copy link
Copy Markdown

Sorry, @fedonman and @serhiy-storchaka, I could not cleanly backport this to 3.15 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 23180c50082fe98784c78511b335d7274ed87fb7 3.15

clin1234 pushed a commit to clin1234/cpython that referenced this pull request Sep 12, 2026
@fedonman @clin1234
pythongh-156953: Fix a reference leak in curses window.insnstr() (pyt…
d816bc9 
…honGH-156954)

insnstr() did not release the bytes object it converted its argument to
when setting the attributes failed, unlike addstr(), addnstr() and
insstr().
@serhiy-storchaka serhiy-storchaka added needs backport to 3.15 pre-release feature fixes, bugs and security fixes and removed needs backport to 3.15 pre-release feature fixes, bugs and security fixes labels Oct 10, 2026
@miss-islington-app

miss-islington-app Bot commented Oct 10, 2026

Copy link
Copy Markdown

Thanks @fedonman for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖

@miss-islington-app

miss-islington-app Bot commented Oct 10, 2026

Copy link
Copy Markdown

Sorry, @fedonman and @serhiy-storchaka, I could not cleanly backport this to 3.15 due to a conflict.

Please backport manually with cherry_picker, see the devguide for more information.

cherry_picker 23180c50082fe98784c78511b335d7274ed87fb7 3.15

@bedevere-app

bedevere-app Bot commented Oct 10, 2026

Copy link
Copy Markdown

GH-159108 is a backport of this pull request to the 3.15 branch.

@bedevere-app bedevere-app Bot removed the needs backport to 3.15 pre-release feature fixes, bugs and security fixes label Oct 10, 2026
serhiy-storchaka added a commit that referenced this pull request Oct 10, 2026
@serhiy-storchaka @fedonman
[3.15] gh-156953: Fix a reference leak in curses window.insnstr() (GH…
c0b9c09 
…-156954) (GH-159108)

insnstr() did not release the bytes object it converted its argument to
when setting the attributes failed, unlike addstr(), addnstr() and
insstr().
(cherry picked from commit 23180c5)

Co-authored-by: Vyron Vasileiadis <hi@fedonman.com>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@serhiy-storchaka serhiy-storchaka serhiy-storchaka approved these changes

Assignees

@serhiy-storchaka serhiy-storchaka

Labels

skip news

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@fedonman @serhiy-storchaka