Found segmentation fault in Pillow

[m-clare]

[m-clare]

Pillow on  main [?] via 🐍 v3.13.0rc2 (pytest-sprint) 
❯ pytest                           
==================================================================== test session starts ====================================================================
platform darwin -- Python 3.13.0rc2, pytest-8.3.3, pluggy-1.5.0
--------------------------------------------------------------------
Pillow 11.0.0.dev0
Python 3.13.0rc2 experimental free-threading build (v3.13.0rc2:ec610069637, Sep  6 2024, 18:09:25) [Clang 15.0.0 (clang-1500.3.9.4)]
--------------------------------------------------------------------
Python executable is /Users/maryannewachter/.virtualenvs/pytest-sprint/bin/python
Environment Python files loaded from /Users/maryannewachter/.virtualenvs/pytest-sprint
System Python files loaded from /Library/Frameworks/PythonT.framework/Versions/3.13
--------------------------------------------------------------------
Python Pillow modules loaded from /Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/PIL
Binary Pillow modules loaded from /Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/PIL
--------------------------------------------------------------------
--- PIL CORE support ok, compiled for 11.0.0.dev0
--- TKINTER support ok, loaded 8.6
--- FREETYPE2 support ok, loaded 2.13.3
--- LITTLECMS2 support ok, loaded 2.16
--- WEBP support ok, loaded 1.4.0
--- JPEG support ok, compiled for libjpeg-turbo 3.0.4
--- OPENJPEG (JPEG2000) support ok, loaded 2.5.2
--- ZLIB (PNG/ZIP) support ok, loaded 1.2.12
--- LIBTIFF support ok, loaded 4.7.0
*** RAQM (Bidirectional Text) support not installed
*** LIBIMAGEQUANT (Quantization method) support not installed
--- XCB (X protocol) support ok
--------------------------------------------------------------------

rootdir: /Users/maryannewachter/workspaces/Pillow
configfile: pyproject.toml
testpaths: Tests
plugins: freethreaded-0.1.0, repeat-0.9.3, timeout-2.3.1, xdist-3.6.1
collected 4595 items / 5 skipped                                                                                                                            

Tests/oss-fuzz/test_fuzzers.py ...................................................................................................................... [  2%]
..................................................................................................................................................... [  5%]
..................................................................................................................................................... [  9%]
..................................................................................................................................................... [ 12%]
..................................................................................................................................................... [ 15%]
..................................................................................................................................................... [ 18%]
..................................................................................................................................................... [ 22%]
.........................Fatal Python error: Segmentation fault

zsh: segmentation fault  pytest
(base) 

[m-clare]

  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000176a57000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Current thread 0x0000000175a4b000 (most recent call first):
  File "/Users/maryannewachter/workspaces/Pillow/Tests/oss-fuzz/test_fuzzers.py", line 64 in test_fuzz_fonts
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/python.py", line 159 in pytest_pyfunc_call
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/python.py", line 1627 in runtest
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 68 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000174a3f000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000173a33000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000172a27000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000171a1b000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000170a0f000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x000000016fa03000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x000000016e9f7000 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 394 in wait_for
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 764 in _wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 729 in wait
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 67 in get_one_result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 58 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/thread.py", line 92 in _worker
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 992 in run
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1041 in _bootstrap_inner
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 1012 in _bootstrap

Thread 0x0000000206ce8f40 (most recent call first):
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/threading.py", line 359 in wait
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/_base.py", line 451 in result
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/_base.py", line 317 in _result_or_cancel
  File "/Library/Frameworks/PythonT.framework/Versions/3.13/lib/python3.13t/concurrent/futures/_base.py", line 619 in result_iterator
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest_freethreaded/plugin.py", line 81 in pytest_runtest_call
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/runner.py", line 242 in <lambda>
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/runner.py", line 341 in from_call
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/runner.py", line 241 in call_and_report
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/runner.py", line 132 in runtestprotocol
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/runner.py", line 113 in pytest_runtest_protocol
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/main.py", line 362 in pytest_runtestloop
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/main.py", line 337 in _main
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/main.py", line 283 in wrap_session
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/main.py", line 330 in pytest_cmdline_main
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/config/__init__.py", line 175 in main
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/_pytest/config/__init__.py", line 201 in console_main
  File "/Users/maryannewachter/.virtualenvs/pytest-sprint/lib/python3.13t/site-packages/pytest/__main__.py", line 9 in <module>
  File "<frozen runpy>", line 88 in _run_code
  File "<frozen runpy>", line 198 in _run_module_as_main

Extension modules: PIL._imaging, PIL._imagingmath, PIL._webp, PIL._imagingft, PIL._imagingcms, PIL._imagingmorph (total: 6)
zsh: segmentation fault  python3 -X dev -m pytest
(base) 

[tonybaloney]

Please can you run again with Python in debug mode.

[m-clare]

Tried with the following after rebuilding with debug (still failing on the fuzzing tests, though I see #10 got past this point)

PYTHON_GIL=0 python -m pytest -x -vvvv --iterations=100 --log-level=DEBUG

Output system/test configuration:

=========================================== test session starts ===========================================
platform darwin -- Python 3.13.0rc2, pytest-8.3.3, pluggy-1.5.0 -- /Users/maryannewachter/.virtualenvs/pytest-debugger/bin/python3
cachedir: .pytest_cache
--------------------------------------------------------------------
Pillow 11.0.0.dev0
Python 3.13.0rc2 experimental free-threading build (main, Oct  2 2024, 21:27:11) [Clang 14.0.0 (clang-1400.0.29.202)]
--------------------------------------------------------------------
Python executable is /Users/maryannewachter/.virtualenvs/pytest-debugger/bin/python3
Environment Python files loaded from /Users/maryannewachter/.virtualenvs/pytest-debugger
System Python files loaded from /usr/local
--------------------------------------------------------------------
Python Pillow modules loaded from /Users/maryannewachter/.virtualenvs/pytest-debugger/lib/python3.13t/site-packages/PIL
Binary Pillow modules loaded from /Users/maryannewachter/.virtualenvs/pytest-debugger/lib/python3.13t/site-packages/PIL
--------------------------------------------------------------------
--- PIL CORE support ok, compiled for 11.0.0.dev0
*** TKINTER support not installed
--- FREETYPE2 support ok, loaded 2.13.3
--- LITTLECMS2 support ok, loaded 2.16
--- WEBP support ok, loaded 1.4.0
--- JPEG support ok, compiled for libjpeg-turbo 3.0.4
--- OPENJPEG (JPEG2000) support ok, loaded 2.5.2
--- ZLIB (PNG/ZIP) support ok, loaded 1.2.12
--- LIBTIFF support ok, loaded 4.7.0
*** RAQM (Bidirectional Text) support not installed
*** LIBIMAGEQUANT (Quantization method) support not installed
--- XCB (X protocol) support ok
--------------------------------------------------------------------

rootdir: /Users/maryannewachter/workspaces/Pillow
configfile: pyproject.toml
testpaths: Tests
plugins: freethreaded-0.1.0
collected 4636 items / 3 skipped                                   

Segfault occurrence:

Tests/oss-fuzz/test_fuzzers.py::test_fuzz_fonts[Tests/fonts/FreeMono.ttf] PASSED                    [ 22%]
Tests/oss-fuzz/test_fuzzers.py::test_fuzz_fonts[Tests/fonts/ter-x20b.pcf] Fatal Python error: Segmentation fault

Thread 0x000000017788f000 (most recent call first):
  File "/Users/maryannewachter/Downloads/Python-3.13.0rc2/Lib/threading.py", line 359 in wait
  File "/Users/maryannewachter/Downloads/Python-3.13.0rc2/Lib/threading.py", line 394 in wait_for
  File "/Users/maryannewachter/Downloads/Python-3.13.0rc2/Lib/threading.py", line 764 in zsh: segmentation fault  PYTHON_GIL=0 python3 -m pytest -x -vvvv --iterations=100 --log-level=DEBUG
(base) 

My system:

$ uname -a
Darwin Maryannes-MBP-2.attlocal.net 23.6.0 Darwin Kernel Version 23.6.0: Mon Jul 29 21:14:30 PDT 2024; root:xnu-10063.141.2~1/RELEASE_ARM64_T6000 arm64

[ngoldbaum]

Here's a C traceback:

Tests/oss-fuzz/test_fuzzers.py ..........................Process 65718 stopped
* thread #4, stop reason = EXC_BAD_ACCESS (code=1, address=0x1a)
    frame #0: 0x00000001009089b8 libfreetype.6.dylib`FT_Done_Face + 68
libfreetype.6.dylib`FT_Done_Face:
->  0x1009089b8 <+68>: ldr    x9, [x1, #0x10]
    0x1009089bc <+72>: cmp    x9, x19
    0x1009089c0 <+76>: b.eq   0x1009089d4    ; <+96>
    0x1009089c4 <+80>: ldr    x1, [x1, #0x8]
Target 0: (python) stopped.
(lldb) bt
* thread #4, stop reason = EXC_BAD_ACCESS (code=1, address=0x1a)
  * frame #0: 0x00000001009089b8 libfreetype.6.dylib`FT_Done_Face + 68
    frame #1: 0x00000001006f497c _imagingft.cpython-313t-darwin.so`font_dealloc + 28
    frame #2: 0x0000000100a76e28 libpython3.13t.dylib`_PyObject_SetManagedDict + 1408
    frame #3: 0x0000000100a76fdc libpython3.13t.dylib`PyObject_ClearManagedDict + 16
    frame #4: 0x0000000100ac5340 libpython3.13t.dylib`subtype_dealloc + 668
    frame #5: 0x0000000100b97924 libpython3.13t.dylib`_PyFrame_ClearLocals + 112
    frame #6: 0x0000000100b97b38 libpython3.13t.dylib`_PyFrame_ClearExceptCode + 428
    frame #7: 0x0000000100b6c1e4 libpython3.13t.dylib`_PyEval_FrameClearAndPop + 148
    frame #8: 0x0000000100b67b44 libpython3.13t.dylib`_PyEval_EvalFrameDefault + 48388
    frame #9: 0x0000000100a21e7c libpython3.13t.dylib`_PyObject_VectorcallDictTstate + 140
    frame #10: 0x0000000100a230cc libpython3.13t.dylib`_PyObject_Call_Prepend + 160
    frame #11: 0x0000000100ac6748 libpython3.13t.dylib`slot_tp_call + 124
    frame #12: 0x0000000100a22084 libpython3.13t.dylib`_PyObject_MakeTpCall + 324
    frame #13: 0x0000000100b5fc0c libpython3.13t.dylib`_PyEval_EvalFrameDefault + 15820
    frame #14: 0x0000000100a25684 libpython3.13t.dylib`method_vectorcall + 328
    frame #15: 0x0000000100c50f58 libpython3.13t.dylib`thread_run + 128
    frame #16: 0x0000000100be6b4c libpython3.13t.dylib`pythread_wrapper + 28
    frame #17: 0x0000000183b65f94 libsystem_pthread.dylib`_pthread_start + 136

It looks like a spawned thread is trying to deallocate an object that wraps a freetype font, and that's seg faulting.

I think freetype2 is supposed to be thread-safe, I wonder what the issue is.

[ngoldbaum]

It looks like freetype internals are corrupt:

* thread #8, stop reason = EXC_BAD_ACCESS (code=1, address=0x16)
    frame #0: 0x00000001016a50e0 libfreetype.6.dylib`FT_Done_Face [inlined] FT_List_Find(list=0x00006000012ec220, data=0x0000000141808200) at ftutil.c:255:17 [opt]
   252 	    cur = list->head;
   253 	    while ( cur )
   254 	    {
-> 255 	      if ( cur->data == data )
   256 	        return cur;
   257
   258 	      cur = cur->next;
Target 0: (python) stopped.
warning: libfreetype.6.dylib was compiled with optimization - stepping may behave oddly; variables may not be available.
(lldb) p cur->data
error: Couldn't apply expression side effects : Couldn't dematerialize a result variable: couldn't read its memory
(lldb) p cur
(FT_ListNode) 0x0000000000000006

[ngoldbaum]

Here's the relevant part of the Freetype2 docs:

https://freetype.org/freetype2/docs/reference/ft2-face_creation.html#ft_face

In particular, this:

An FT_Face object can only be safely used from one thread at a time. Similarly, creation and destruction of FT_Face with the same FT_Library object can only be done from one thread at a time.

So Pillow needs to enforce that, or add some locking. I'll open an issue against Pillow with these details.

[m-clare]

Neat (and thanks)! @ngoldbaum how did you generate the C traceback? I was surprised I didn't get more information than what I showed above building python with ./configure --with-pydebug --disable-gil, so I was wondering if I was missing some additional flags at runtime.

[ngoldbaum]

I was running python under lldb. CPython might in principle be able to print a C traceback but in practice it doesn't and you need a C debugger and libraries with debug symbols to be able to get a meaningful C traceback.

[radarhere]

python-pillow/Pillow#8454 has now been resolved in Pillow main by python-pillow/Pillow#8496