gh-154848: Enforce frame boundaries in the C unpickler - #154893
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serhiy-storchaka merged 3 commits intoJul 31, 2026
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The C unpickler did not enforce PEP 3154 frame boundaries: an opcode or its argument could straddle a frame, and a new frame could begin before the previous one ended. Such reads now raise UnpicklingError, as in the pure Python implementation. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
serhiy-storchaka
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needs backport to 3.13
An opcode is a single byte and cannot straddle a frame boundary; only an argument can. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The tests only use opcodes available in protocol 4 (FRAME being the newest), so the PROTO header now declares protocol 4 instead of 5. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
serhiy-storchaka
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needs backport to 3.15
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Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15. |
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Sorry, @serhiy-storchaka, I could not cleanly backport this to |
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GH-154977 is a backport of this pull request to the 3.15 branch. |
bedevere-app
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needs backport to 3.15
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Sorry, @serhiy-storchaka, I could not cleanly backport this to |
This was referenced Jul 31, 2026
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GH-154981 is a backport of this pull request to the 3.14 branch. |
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GH-154982 is a backport of this pull request to the 3.13 branch. |
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) (GH-154977) The C unpickler did not enforce PEP 3154 frame boundaries: an opcode or its argument could straddle a frame, and a new frame could begin before the previous one ended. Such reads now raise UnpicklingError, as in the pure Python implementation. (cherry picked from commit 10a8454) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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The C unpickler did not enforce PEP 3154 frame boundaries: an opcode or its argument could straddle a frame, and a new frame could begin before the previous one ended. Reads simply continued across the boundary.
So
pickle.loads()could produce a different object thanpickletools.dis()shows for the same bytes — e.g. a pickle that disassembles as a plainBINBYTESbut callsbuiltins.printon load. The pure-Python unpickler already rejects these.Such reads now raise
UnpicklingError, matching the pure-Python implementation, with no overhead on the unframed read path.