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[3.8] bpo-38395: Fix ownership in weakref.proxy methods (GH-16632) #16662

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merged 1 commit into from Oct 8, 2019

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@pablogsal pablogsal commented Oct 8, 2019

The implementation of weakref.proxy's methods call back into the Python
API using a borrowed references of the weakly referenced object
(acquired via PyWeakref_GET_OBJECT). This API call may delete the last
reference to the object (either directly or via GC), leaving a dangling
pointer, which can be subsequently dereferenced.

To fix this, claim a temporary ownership of the referenced object when
calling the appropriate method. Some functions because at the moment they
do not need to access the borrowed referent, but to protect against
future changes to these functions, ownership need to be fixed in
all potentially affected methods..
(cherry picked from commit 10cd00a)

Co-authored-by: Pablo Galindo Pablogsal@gmail.com

Automerge-Triggered-By: @pablogsal

https://bugs.python.org/issue38395

The implementation of weakref.proxy's methods call back into the Python
API using a borrowed references of the weakly referenced object
(acquired via PyWeakref_GET_OBJECT). This API call may delete the last
reference to the object (either directly or via GC), leaving a dangling
pointer, which can be subsequently dereferenced.

To fix this, claim a temporary ownership of the referenced object when
calling the appropriate method. Some functions because at the moment they
do not need to access the borrowed referent, but to protect against
future changes to these functions, ownership need to be fixed in
all potentially affected methods..
(cherry picked from commit 10cd00a)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
@pablogsal pablogsal added the 🤖 automerge PR will be merged once it's been approved and all CI passed label Oct 8, 2019
@pablogsal pablogsal closed this Oct 8, 2019
@pablogsal pablogsal reopened this Oct 8, 2019
@pablogsal pablogsal merged commit 526ef85 into python:3.8 Oct 8, 2019
1 check was pending
@pablogsal pablogsal deleted the backport-10cd00a-3.8 branch Oct 8, 2019
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