[New-bugs-announce] [issue9960] test_structmembers fails on s390x (bigendian 64-bit): int/Py_ssize_t issue
report at bugs.python.org
Mon Sep 27 17:11:36 CEST 2010
New submission from Dave Malcolm <dmalcolm at redhat.com>:
test test_structmembers crashed -- <type 'exceptions.ValueError'>:
string too long
Traceback (most recent call last):
File "/builddir/build/BUILD/Python-2.7/Lib/test/regrtest.py", line 863, in runtest_inner
the_package = __import__(abstest, globals(), locals(), )
File "/builddir/build/BUILD/Python-2.7/Lib/test/test_structmembers.py", line 12, in <module>
9.99999, 10.1010101010, "hi")
ValueError: string too long
_testcapimodule.c: test_structmembers_new's fmt has:
and these args:
for grabbing this data:
const char *s = NULL;
Py_ssize_t string_len = 0;
However, the module doesn't define PY_SSIZE_T_CLEAN, which leads to &string_len being treated as an (int*) rather than a (Py_ssize_t*) and thus written to with just the first 32-bits of the size, rather than the full size.
The PyArgs_ call without PY_SSIZE_T_CLEAN writes the size of the string (2) through (int*)&string_len, writing 0x00000002 to the first 4 bytes, setting the 64-bit "string_len" value to 0x0000000200000000 i.e. 2^34, wildly too large for the iirc 5 byte buffer.
Confirmed in gdb:
(gdb) p string_len
$2 = 8589934592
(gdb) p /x string_len
$3 = 0x200000000
Am attaching a patch (against 2.7 maintenance branch) which defines PY_SSIZE_T_CLEAN; doing so requires updating another int to be a Py_ssize_t in that module, within test_u_code.
http://docs.python.org/c-api/arg.html lists "u# (Unicode) [Py_UNICODE *, int]" and has no reference to the effect of PY_SSIZE_T_CLEAN on the "u#" format specifier. My reading of Python/getargs.c is that this macro does affect "u#" in a manner analogous to "s#"; does this documentation need clarifying?
keywords: easy, patch
stage: patch review
title: test_structmembers fails on s390x (bigendian 64-bit): int/Py_ssize_t issue
versions: Python 2.7
Added file: http://bugs.python.org/file19029/python-test_structmembers.patch
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