[3.7] bpo-9263: _PyObject_Dump() detects freed memory (GH-10061) by vstinner · Pull Request #10662 · python/cpython (original) (raw)

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_PyObject_Dump() now uses an heuristic to check if the object memory has been freed: log "" in that case.

The heuristic rely on the debug hooks on Python memory allocators which fills the memory with DEADBYTE (0xDB) when memory is deallocated. Use PYTHONMALLOC=debug to always enable these debug hooks.

(cherry picked from commit 82af0b6)

If _PyObject_Dump() detects that the object is freed, don't try to dump it (exit immediately).

Enhance also _PyObject_IsFreed(): it now detects if the pointer itself looks like freed memory.

(cherry picked from commit 2cf5d32)

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.6.
🐍🍒⛏🤖

Sorry, @vstinner, I could not cleanly backport this to 3.6 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 95036ea25d47f0081bda2ba96ea327f3375cb6a4 3.6

vstinner added a commit that referenced this pull request

Nov 22, 2018

…GH-10663)

• bpo-9263: _PyObject_Dump() detects freed memory (GH-10061)

_PyObject_Dump() now uses an heuristic to check if the object memory has been freed: log "" in that case.

The heuristic rely on the debug hooks on Python memory allocators which fills the memory with DEADBYTE (0xDB) when memory is deallocated. Use PYTHONMALLOC=debug to always enable these debug hooks.

(cherry picked from commit 82af0b6)

• bpo-9263: Fix _PyObject_Dump() for freed object (#10661)

If _PyObject_Dump() detects that the object is freed, don't try to dump it (exit immediately).

Enhance also _PyObject_IsFreed(): it now detects if the pointer itself looks like freed memory.

(cherry picked from commit 2cf5d32) (cherry picked from commit 95036ea)