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GeezerVison is showing github.com — gh-159739: Handle overlapping buffers in struct.pack_into by jelle-openai · Pull Request #159985 · python/cpython

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@jelle-openai

@jelle-openai jelle-openai commented Oct 20, 2026 •
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Handle overlapping buffers in struct.pack_into. struct.pack_into() can use the same bytearray as both the destination and an s or p value. The copy then passes overlapping regions to memcpy, which is undefined in C and can produce platform-dependent results or a sanitizer abort. memmove makes the overlapping copy defined.

Backport to 3.15 and 3.14.

  • Issue: Fix minor safety issues #159739

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@jelle-openai
pythongh-159739: Handle overlapping buffers in struct.pack_into
e5efeee 
Backport to 3.15 and 3.14.
@bedevere-app bedevere-app Bot mentioned this pull request Oct 20, 2026
Fix minor safety issues #159739
Open
@bedevere-app bedevere-app Bot added the awaiting review label Oct 20, 2026
@JelleZijlstra JelleZijlstra added needs backport to 3.14 bugs and security fixes needs backport to 3.15 bugs and security fixes labels Oct 20, 2026
@JelleZijlstra
JelleZijlstra enabled auto-merge (squash) October 21, 2026 18:47
@JelleZijlstra
JelleZijlstra merged commit 31a7d99 into python:main Oct 21, 2026
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@miss-islington-app

miss-islington-app Bot commented Oct 21, 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.
🐍🍒⛏🤖
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@bedevere-app bedevere-app Bot removed the awaiting review label Oct 21, 2026
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bedevere-app Bot commented Oct 21, 2026

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GH-160101 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 21, 2026
@miss-islington-app

miss-islington-app Bot commented Oct 21, 2026

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Sorry, @jelle-openai and @JelleZijlstra, I could not cleanly backport this to 3.14 due to a conflict.

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

cherry_picker 31a7d994a559a421814ca9e8edfcab21ae4a5b36 3.14
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@miss-islington-app miss-islington-app Bot assigned JelleZijlstra Oct 21, 2026
JelleZijlstra pushed a commit that referenced this pull request Oct 22, 2026
@miss-islington @jelle-openai
[3.15] gh-159739: Handle overlapping buffers in struct.pack_into (GH-…
08fd98b 
…159985) (#160101)

`struct.pack_into()` can use the same bytearray as both the destination and an `s` or `p` value. The copy then passes overlapping regions to `memcpy`, which is undefined in C and can produce platform-dependent results or a sanitizer abort. `memmove` makes the overlapping copy defined.
(cherry picked from commit 31a7d99)

Co-authored-by: Jelle Zijlstra <[email protected]>
@jelle-openai jelle-openai mentioned this pull request Oct 23, 2026
[3.14] gh-159739: Handle overlapping buffers in struct.pack_into (GH-159985) #160484
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bedevere-app Bot commented Oct 23, 2026

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GH-160484 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 23, 2026
gpshead pushed a commit that referenced this pull request Nov 9, 2026
@jelle-openai
[3.14] gh-159739: Handle overlapping buffers in struct.pack_into (GH-…
a96096c 
…159985) (#160484)

`struct.pack_into()` can use the same bytearray as both the destination and an `s` or `p` value. The copy then passes overlapping regions to `memcpy`, which is undefined in C and can produce platform-dependent results or a sanitizer abort. `memmove` makes the overlapping copy defined.
(cherry picked from commit 31a7d99)
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