bash security update

CentOS Errata and Security Advisory CESA-2011:1073

Bash is the default shell for Red Hat Enterprise Linux.

It was found that certain scripts bundled with the Bash documentation
created temporary files in an insecure way. A malicious, local user could
use this flaw to conduct a symbolic link attack, allowing them to overwrite
the contents of arbitrary files accessible to the victim running the
scripts. (CVE-2008-5374)

This update fixes the following bugs:

• When using the source builtin at location “.”, occasionally, bash
  opted to preserve internal consistency and abort scripts. This caused
  bash to abort scripts that assigned values to read-only variables.
  This is now fixed to ensure that such scripts are now executed as
  written and not aborted. (BZ#448508)

• When the tab key was pressed for auto-completion options for the typed
  text, the cursor moved to an unexpected position on a previous line if
  the prompt contained characters that cannot be viewed and a “]”. This
  is now fixed to retain the cursor at the expected position at the end of
  the target line after autocomplete options correctly display. (BZ#463880)

• Bash attempted to interpret the NOBITS .dynamic section of the ELF
  header. This resulted in a “^D: bad ELF interpreter: No such
  file or directory” message. This is fixed to ensure that the invalid
  “^D” does not appear in the error message. (BZ#484809)

• The $RANDOM variable in Bash carried over values from a previous
  execution for later jobs. This is fixed and the $RANDOM variable
  generates a new random number for each use. (BZ#492908)

• When Bash ran a shell script with an embedded null character, bash’s
  source builtin parsed the script incorrectly. This is fixed and
  bash’s source builtin correctly parses shell script null characters.
  (BZ#503701)

• The bash manual page for “trap” did not mention that signals ignored upon
  entry cannot be listed later. The manual page was updated for this update
  and now specifically notes that “Signals ignored upon entry to the shell
  cannot be trapped, reset or listed”. (BZ#504904)

• Bash’s readline incorrectly displayed additional text when resizing
  the terminal window when text spanned more than one line, which caused
  incorrect display output. This is now fixed to ensure that text in more
  than one line in a resized window displays as expected. (BZ#525474)

• Previously, bash incorrectly displayed “Broken pipe” messages for
  builtins like “echo” and “printf” when output did not succeed due to
  EPIPE. This is fixed to ensure that the unnecessary “Broken pipe”
  messages no longer display. (BZ#546529)

• Inserts with the repeat function were not possible after a deletion in
  vi-mode. This has been corrected and, with this update, the repeat function
  works as expected after a deletion. (BZ#575076)

• In some situations, bash incorrectly appended “/” to files instead of
  just directories during tab-completion, causing incorrect
  auto-completions. This is fixed and auto-complete appends “/” only to
  directories. (BZ#583919)

• Bash had a memory leak in the “read” builtin when the number of fields
  being read was not equal to the number of variables passed as arguments,
  causing a shell script crash. This is fixed to prevent a memory leak and
  shell script crash. (BZ#618393)

• /usr/share/doc/bash-3.2/loadables in the bash package contained source
  files which would not build due to missing C header files. With this
  update, the unusable (and unbuildable) source files were removed from the
  package. (BZ#663656)

This update also adds the following enhancement:

• The system-wide “/etc/bash.bash_logout” bash logout file is now enabled.
  This allows administrators to write system-wide logout actions for all
  users. (BZ#592979)

Users of bash are advised to upgrade to this updated package, which
contains backported patches to resolve these issues and add this
enhancement.

Merged security bulletin from advisories:
https://lists.centos.org/pipermail/centos-announce/2011-September/079922.html
https://lists.centos.org/pipermail/centos-announce/2011-September/079929.html
https://lists.centos.org/pipermail/centos-cr-announce/2011-September/026274.html
https://lists.centos.org/pipermail/centos-cr-announce/2011-September/026275.html

Affected packages:
bash

Upstream details at:
https://access.redhat.com/errata/RHSA-2011:1073