gh-154848: Enforce frame boundaries in the C unpickler - #154893
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serhiy-storchaka wants to merge 3 commits into
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gh-154848: Enforce frame boundaries in the C unpickler#154893serhiy-storchaka wants to merge 3 commits into
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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
added
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>
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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.