From 1a9a5907a6259590cb8484b401a00d0cd0c3127e Mon Sep 17 00:00:00 2001 From: Ronald Oussoren Date: Sat, 23 Dec 2023 13:33:34 +0100 Subject: [PATCH] gh-74573: document that ndbm can silently corrupt databases on macOS (GH-113354) * gh-74573: document that ndbm can silently corrupt databases on macOS The system ndbm implementation on macOS has an undocumented limitation on the size of values and can silently corrupt database files when those are exceeded. (cherry picked from commit 593b4d81d276b428f926debfe70d56ba94edf0e1) Co-authored-by: Ronald Oussoren Co-authored-by: Erlend E. Aasland --- Doc/library/dbm.rst | 7 +++++++ Doc/library/shelve.rst | 3 +++ .../macOS/2023-12-21-11-53-47.gh-issue-74573.MA6Vys.rst | 3 +++ 3 files changed, 13 insertions(+) create mode 100644 Misc/NEWS.d/next/macOS/2023-12-21-11-53-47.gh-issue-74573.MA6Vys.rst diff --git a/Doc/library/dbm.rst b/Doc/library/dbm.rst index 2be499337a2a15..8b799ad6cb57fd 100644 --- a/Doc/library/dbm.rst +++ b/Doc/library/dbm.rst @@ -265,6 +265,13 @@ This module can be used with the "classic" ndbm interface or the GNU GDBM compatibility interface. On Unix, the :program:`configure` script will attempt to locate the appropriate header file to simplify building this module. +.. warning:: + + The ndbm library shipped as part of macOS has an undocumented limitation on the + size of values, which can result in corrupted database files + when storing values larger than this limit. Reading such corrupted files can + result in a hard crash (segmentation fault). + .. exception:: error Raised on :mod:`dbm.ndbm`-specific errors, such as I/O errors. :exc:`KeyError` is raised diff --git a/Doc/library/shelve.rst b/Doc/library/shelve.rst index 88802d717d7383..95c54991887022 100644 --- a/Doc/library/shelve.rst +++ b/Doc/library/shelve.rst @@ -113,6 +113,9 @@ Restrictions differs across Unix versions and requires knowledge about the database implementation used. +* On macOS :mod:`dbm.ndbm` can silently corrupt the database file on updates, + which can cause hard crashes when trying to read from the database. + .. class:: Shelf(dict, protocol=None, writeback=False, keyencoding='utf-8') diff --git a/Misc/NEWS.d/next/macOS/2023-12-21-11-53-47.gh-issue-74573.MA6Vys.rst b/Misc/NEWS.d/next/macOS/2023-12-21-11-53-47.gh-issue-74573.MA6Vys.rst new file mode 100644 index 00000000000000..96dcd4765d95da --- /dev/null +++ b/Misc/NEWS.d/next/macOS/2023-12-21-11-53-47.gh-issue-74573.MA6Vys.rst @@ -0,0 +1,3 @@ +Document that :mod:`dbm.ndbm` can silently corrupt DBM files on updates when +exceeding undocumented platform limits, and can crash (segmentation fault) +when reading such a corrupted file. (FB8919203)