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@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.