[issue19568] bytearray_setslice_linear() leaves the bytearray in an inconsistent state on memory allocation failure

[STINNER Victor]

New submission from STINNER Victor:

When bytearray_setslice_linear() is called to shrink the buffer with lo=0 and PyByteArray_Resize() fails because of a memory error, the bytearray is leaved in an inconsistent state: ob_start has been updated but not the size.

I found the issue using failmalloc: test_nonblock_pipe_write_smallbuf() of test_io does fail with an assertion error when testing the _pyio module which uses bytearray for the write buffer.

Attached patch restores the bytearray in its previous state if PyByteArray_Resize() failed.

I prefer to only fix the issue in Python 3.4 because it is unlikely and I prefer to not introduce regressions in previous Python versions.


I made a similar fix for list:

changeset:   84717:3f25a7dd8346
user:        Victor Stinner <victor.stinner at gmail.com>
date:        Fri Jul 19 23:06:21 2013 +0200
files:       Objects/listobject.c
description:
Issue #18408: Fix list_ass_slice(), handle list_resize() failure

I tested the patch manually by injecting a fault using gdb: list items are correctly restored on failure.

----------
files: bytearray_setslice_mem_error.patch
keywords: patch
messages: 202736
nosy: haypo, serhiy.storchaka
priority: normal
severity: normal
status: open
title: bytearray_setslice_linear() leaves the bytearray in an inconsistent state on memory allocation failure
versions: Python 3.4
Added file: http://bugs.python.org/file32593/bytearray_setslice_mem_error.patch

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