Description

YuanchengJiang

opened on Dec 16, 2025

Issue body actions

Crash report

What happened?

import sqlite3

# 1. Setup an in-memory database with a BLOB column
con = sqlite3.connect(':memory:')
con.execute('create table test(b blob)')

# 2. Insert a small amount of data.
# The unicode character '\u2603' (Snowman) is 3 bytes in UTF-8 (b'\xe2\x98\x83').
# The blob size will be 3.
con.execute('insert into test(b) values (?)', ('\u2603',))

# 3. Open the BLOB for incremental I/O
# Table: 'test', Column: 'b', Row: 1
blob = con.blobopen('test', 'b', 1)

# 4. Trigger the crash
# We request a slice starting at index 5 (which is beyond the blob size of 3)
# and ending at index -5 (which wraps around to before the start).
# This combination causes the internal 'offset' calculation in C to assert
# failing that the offset (5) is not less than the blob bytes (3).
blob[5:-5]

python: ../Modules/_sqlite/blob.c:146: PyObject *read_multiple(pysqlite_Blob *, Py_ssize_t, Py_ssize_t): Assertion `offset < sqlite3_blob_bytes(self->blob)' failed.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

Linked PRs

• gh-142787: Fix assertion failure in sqlite3 blob slice #142824
• [3.14] gh-142787: Handle empty sqlite3 blob slices (GH-142824) #145297
• [3.13] gh-142787: Handle empty sqlite3 blob slices (GH-142824) #145298

Activity

1. YuanchengJiang

   added

   type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump

   on Dec 16, 2025
2. StanFromIreland

   added

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   topic-sqlite3

   on Dec 16, 2025
3. github-project-automation

   added this to sqlite3 issueson Dec 16, 2025
4. abdoulrasheed

   added a commit that references this issue on Dec 16, 2025

   pythongh-142787: Fix assertion failure in sqlite3 blob slice

   97ca005
5. erlend-aasland

   moved this to In Progress in sqlite3 issueson Dec 16, 2025
6. abdoulrasheed

   added a commit that references this issue on Dec 16, 2025

   Add regression test for pythongh-142787

   c7a12b3
7. erlend-aasland

   linked a pull request that will close this issuegh-142787: Fix assertion failure in sqlite3 blob slice #142824on Feb 26, 2026
8. erlend-aasland

   added a commit that references this issue on Feb 26, 2026

   gh-142787: Handle empty sqlite3 blob slices (#142824)

   06b0920
9. erlend-aasland

   closed this as completedin #142824on Feb 26, 2026
10. github-project-automation

    moved this from In Progress to Done in sqlite3 issueson Feb 26, 2026
11. miss-islington

    added 2 commits that reference this issue on Feb 26, 2026

    pythongh-142787: Handle empty sqlite3 blob slices (pythonGH-142824)

    04cab0e

    pythongh-142787: Handle empty sqlite3 blob slices (pythonGH-142824)

    de537f0
12. erlend-aasland

    added 2 commits that reference this issue on Feb 27, 2026

    [3.14] gh-142787: Handle empty sqlite3 blob slices (GH-142824) (#145297)

    bc6a7a2

    [3.13] gh-142787: Handle empty sqlite3 blob slices (GH-142824) (#145298)

    cd3e9b3
13. erlend-aasland commented on Feb 27, 2026

    

    erlend-aasland

    on Feb 27, 2026

    Contributor

    More actions

    Thanks for the report, @YuanchengJiang, and thanks for the fix @abdoulrasheed!
14. brijkapadia

    added a commit that references this issue on Feb 28, 2026

    pythongh-142787: Handle empty sqlite3 blob slices (python#142824)

    26a469c
15. ljfp

    added a commit that references this issue on Apr 25, 2026

    pythongh-142787: Handle empty sqlite3 blob slices (python#142824)

    9fbeae8

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