RHBA-2011:1564 - Bug Fix Advisory

Topic

Updated python packages that fix several bugs and add an enhancement are now
available for Red Hat Enterprise Linux 6.

Description

Python is an interpreted, interactive, object-oriented programming language.

This update fixes the following bugs:

• The Python standard library contains numerous APIs that handle the uid_t and

gid_t attributes, which contain unsigned 32-bit values. Previously, the existing
code often passed the values as C language long values, which are signed 32-bit
values on 32-bit architectures. Consequently, negative integer objects occurred
when a uid_t/gid_t value was equal or larger than 2^31 on 32-bit architectures.
With this update, the standard library has been updated throughout to accept the
full range of uid_t/gid_t values (0 through 2^32-1), using "int" objects for
small values, but using "long" objects where needed to avoid integer overflow.
As a special case, "-1" is also supported, as this value has special meaning for
the os.chown() function and other related functions. (BZ#697470)

• Previously, the multiprocessing module used the "select" system call to

communicate with subprocesses, limiting the number of file descriptors to the
value of the FD_SETSIZE variable (1024). With this update, the multiprocessing
module has been ported to use the "poll" system call, instead of "select", thus
fixing this bug. (BZ#713082)

• Previously, a race condition sometimes caused the forking.Popen.poll() method

of the multiprocessing module to terminate with the "OSError: [Errno 10] No
child processes" error message when starting subprocesses. This bug has been
fixed and the crashes no longer occur in the described scenario. (BZ#685234)

• Previously, the getpass.getpass() method discarded Ctrl-C and Ctrl-Z input,

requiring the user to press Ctrl-D to exit the password entry prompt and then
returning traceback error messages. With this update, the described user input
is processed properly by the getpass.getpass() method. (BZ#689794)

• Due to a bug, the readline.get_history_length() and

readline.get_history_item() methods leaked memory when executed. This bug has
been fixed and no longer occurs. (BZ#699740)

• When building the C extension modules, if a value for the CFLAGS variable is

defined in the environment, it is appended to the compilation flags from
Python's Makefile. Due to a bug, only flags stored in the OPT variable were
supplied from the Makefile. Consequently, the "-fno-strict-aliasing" flag was
missing and build errors occurred. This bug has been fixed, CFLAGS are properly
appended to the original Python build string, and no build errors are now
returned in the described scenario. (BZ#727364)

• When feeding data to the standard input of short-lived processes, the

subprocess.Popen.communicate() method sometimes terminated with the "OSError:
[Errno 32] Broken pipe" error message. This bug has been fixed and the crashes
no longer occur in the described scenario. (BZ#667431)

This update adds the following enhancement:

• The gdb (GNU Debugger) Python hooks for debugging Python itself (via the

python-debuginfo package) have been enhanced. The hooks now report if a thread
is waiting on a lock, such as the GIL (Global Interpreter Lock), and call to
appropriate C functions, methods, and garbage collections. In addition, the
hooks have been optimized to provide at least file and function names, when line
numbers and locals are not available. (BZ#711818)

All users of python are advised to upgrade to these updated packages, which fix
these bugs and add this enhancement.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 667431 - Python Popen.communicate is unable to collect stderr, stdout and returncode for a short lived processes
• BZ - 685234 - multiprocessing.Process.start() fails occasionally
• BZ - 689794 - ctrl+c does not work during python getpass.getpass() (was: Unable to terminate sss_obfuscate)
• BZ - 697470 - os.lstat() returns negative values for owner and/or group for huge UID/GIDs on i386
• BZ - 713082 - multiprocessing.Pipe problem: "handle out of range in select()"
• BZ - 727364 - Setting environ['CFLAGS'] in a distutils setup.py file results in missing compile flags

CVEs

(none)

References

(none)