Segfaults with dict

[Clint Byrum]

In certain situations python3.5 will segfault. This bug is confirmed and fixed upstream in Python 3.5.4

http://bugs.python.org/issue27945

[Test Case]
1. download attached bpo-27945.py
2. run: python3.5 bpo-27945.py

If it does not segfault, the bug is fixed.

[Regression Potential]
The fix has been shown to introduce a minor performance hit for dictionaries in general.

[Monty Taylor (mordred)]

Patch to apply fix for bpo-27945 to 3.5.2.

[Clint Byrum (clint-fewbar)]

This python script reproduces the segfault when run via python3.5

[Clint Byrum (clint-fewbar)]

Python3.5 has been removed from artful, and thus does not need to be fixed.

[Clint Byrum (clint-fewbar)]

The attached patch is also included in Python 3.6.2 upstream, which is released in artful.

[Monty Taylor (mordred)]

The quilt patch (and upstream bugfix) adds unit test test_fromkeys_operator_modifying_dict_operand which demonstrate a reproducer which has been verified to fail on xenial 3.5.2 and to work after applying the patch.

[Chris Halse Rogers (raof)]

An upload of python3.5 to xenial-proposed has been rejected from the upload queue for the following reason: "Bug# 1682934 is missing SRU testcase/impact/regresison potential; all bugs are missing a Zesty upload which is requried before we could release the Xenial update.".

[Clint Byrum (clint-fewbar)]

Uploaded for zesty as well.

[Clint Byrum (clint-fewbar)]

I've uploaded just this fix to xenial and zesty, without the other bug which isn't SRU-ready yet. Thanks for your review raof!

[Clint Byrum (clint-fewbar)]

Uploaded to python3.6 for zesty too.

[Brian Murray (brian-murray)]

Hello Clint, or anyone else affected,

Accepted python3.6 into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/python3.6/3.6.1-1ubuntu0~17.04.0 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Brian Murray (brian-murray)]

Hello Clint, or anyone else affected,

Accepted python3.5 into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/python3.5/3.5.2-2ubuntu0~16.04.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Simon Déziel (sdeziel)]

On Xenial, before:

$ python3.5 bpo-27945.py
Segmentation fault

After applying 3.5.2-2ubuntu0~16.04.2:

$ python3.5 bpo-27945.py
Traceback (most recent call last):
  File "bpo-27945.py", line 7, in <module>
    for result in d.items():
RuntimeError: dictionary changed size during iteration

[Simon Déziel (sdeziel)]

On Zesty, before with python3.6:

$ python3.6 /tmp/bpo-27945.py
Segmentation fault

After applying 3.6.1-1ubuntu0~17.04.0:

$ python3.6 /tmp/bpo-27945.py
Traceback (most recent call last):
  File "/tmp/bpo-27945.py", line 7, in <module>
    for result in d.items():
RuntimeError: dictionary changed size during iteration
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook
    from apport.fileutils import likely_packaged, get_recent_crashes
  File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>
    from apport.report import Report
  File "/usr/lib/python3/dist-packages/apport/report.py", line 30, in <module>
    import apport.fileutils
  File "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in <module>
    from apport.packaging_impl import impl as packaging
  File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 24, in <module>
    import apt
  File "/usr/lib/python3/dist-packages/apt/__init__.py", line 23, in <module>
    import apt_pkg
ModuleNotFoundError: No module named 'apt_pkg'

Original exception was:
Traceback (most recent call last):
  File "/tmp/bpo-27945.py", line 7, in <module>
    for result in d.items():
RuntimeError: dictionary changed size during iteration

The except hook error is unrelated.

[Brian Murray (brian-murray)]

Hello Clint, or anyone else affected,

Accepted python3.5 into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/python3.5/3.5.3-1ubuntu0~17.04.0 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Simon Déziel (sdeziel)]

On Zesty, before with python3.5:

$ python3.5 /tmp/bpo-27945.py
Segmentation fault

After applying 3.5.3-1ubuntu0~17.04.0:

$ python3.5 /tmp/bpo-27945.py
Traceback (most recent call last):
  File "/tmp/bpo-27945.py", line 7, in <module>
    for result in d.items():
RuntimeError: dictionary changed size during iteration

[Łukasz Zemczak (sil2100)]

The xenial upload looks good. I'll be accepting it once I release the previous python3.5 package that's in -proposed (I'll do that on Monday since Friday releases to -updates are never a good idea).

[Launchpad Janitor (janitor)]

This bug was fixed in the package python3.6 - 3.6.1-1ubuntu0~17.04.0

---------------
python3.6 (3.6.1-1ubuntu0~17.04.0) zesty; urgency=medium

  * SRU: LP: #1711724 Fix dict segfault. Issue #27945.

 -- Clint Byrum <email address hidden> Thu, 07 Sep 2017 09:36:03 -0700

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for python3.6 has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package python3.5 - 3.5.3-1ubuntu0~17.04.0

---------------
python3.5 (3.5.3-1ubuntu0~17.04.0) zesty; urgency=medium

  * SRU: LP: #1711724 Fix dict segfault. Issue #27945.

 -- Clint Byrum <email address hidden> Thu, 07 Sep 2017 09:23:57 -0700

[Launchpad Janitor (janitor)]

This bug was fixed in the package python3.5 - 3.5.2-2ubuntu0~16.04.2

---------------
python3.5 (3.5.2-2ubuntu0~16.04.2) xenial; urgency=medium

  * SRU: LP: #1711724 Fix dict segfault. Issue #27945.

 -- Clint Byrum <email address hidden> Fri, 18 Aug 2017 10:48:00 -0700