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GeezerVison is showing github.com — gh-159739: Recheck BytesIO state after converting truncate size by jelle-openai · Pull Request #160190 · python/cpython

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@jelle-openai

@jelle-openai jelle-openai commented Oct 22, 2026 •
edited by bedevere-app Bot
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A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.

  • Issue: Fix minor safety issues #159739

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@jelle-openai
pythongh-159739: Recheck BytesIO state after converting truncate size
3d898fd 
A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.
@bedevere-app bedevere-app Bot added the awaiting review label Oct 22, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Oct 22, 2026
Fix minor safety issues #159739
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JelleZijlstra
JelleZijlstra reviewed Oct 22, 2026
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Comment thread Misc/NEWS.d/next/Library/2026-10-21-21-26-10.gh-issue-159739.rVWF2a.rst Resolved

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@JelleZijlstra
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JelleZijlstra merged commit 8bfda55 into python:main Oct 22, 2026
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@JelleZijlstra JelleZijlstra added needs backport to 3.14 bugs and security fixes needs backport to 3.15 bugs and security fixes labels Oct 22, 2026
@bedevere-app bedevere-app Bot removed the awaiting review label Oct 22, 2026
@miss-islington-app

miss-islington-app Bot commented Oct 22, 2026

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Thanks @jelle-openai for the PR, and @JelleZijlstra for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!
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@miss-islington-app

miss-islington-app Bot commented Oct 22, 2026

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Thanks @jelle-openai for the PR, and @JelleZijlstra for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖
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@miss-islington-app

miss-islington-app Bot commented Oct 22, 2026

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Thanks @jelle-openai for the PR, and @JelleZijlstra for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖
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miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Oct 22, 2026
@jelle-openai @miss-islington
pythongh-159739: Recheck BytesIO state after converting truncate size (…
7ba9084 
…pythonGH-160190)

A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.
(cherry picked from commit 8bfda55)

Co-authored-by: Jelle Zijlstra <[email protected]>
@bedevere-app

bedevere-app Bot commented Oct 22, 2026

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GH-160384 is a backport of this pull request to the 3.15 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.15 bugs and security fixes label Oct 22, 2026
@bedevere-app

bedevere-app Bot commented Oct 22, 2026

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GH-160385 is a backport of this pull request to the 3.14 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Oct 22, 2026
@miss-islington-app

miss-islington-app Bot commented Oct 22, 2026

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Sorry @jelle-openai and @JelleZijlstra, I had trouble completing the backport.

Please retry by removing and re-adding the "needs backport to 3.14" label.
If that does not work, please backport manually with cherry_picker, see the devguide for more information.

cherry_picker 8bfda5553c0f8ac1163b4ce4ca7b8b632a853f51 3.14
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@miss-islington-app miss-islington-app Bot assigned JelleZijlstra Oct 22, 2026
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Oct 22, 2026
@jelle-openai @miss-islington
pythongh-159739: Recheck BytesIO state after converting truncate size (…
e3464fa 
…pythonGH-160190)

A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.
(cherry picked from commit 8bfda55)

Co-authored-by: Jelle Zijlstra <[email protected]>
@miss-islington-app

miss-islington-app Bot commented Oct 22, 2026

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Sorry @jelle-openai and @JelleZijlstra, I had trouble completing the backport.

Please retry by removing and re-adding the "needs backport to 3.15" label.
If that does not work, please backport manually with cherry_picker, see the devguide for more information.

cherry_picker 8bfda5553c0f8ac1163b4ce4ca7b8b632a853f51 3.15
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JelleZijlstra pushed a commit that referenced this pull request Oct 23, 2026
@miss-islington @jelle-openai
[3.15] gh-159739: Recheck BytesIO state after converting truncate size (
45f5b00 
GH-160190) (#160384)

A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.
(cherry picked from commit 8bfda55)

Co-authored-by: Jelle Zijlstra <[email protected]>
JelleZijlstra pushed a commit that referenced this pull request Oct 23, 2026
@miss-islington @jelle-openai
[3.14] gh-159739: Recheck BytesIO state after converting truncate size (
4a455fe 
GH-160190) (#160385)

A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.
(cherry picked from commit 8bfda55)

Co-authored-by: Jelle Zijlstra <[email protected]>
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