RHSA-2011:1073 - Security Advisory

Topic

An updated bash package that fixes one security issue, several bugs, and
adds one enhancement is now available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having low
security impact. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available from the CVE link in
the References section.

Description

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.

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
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 448508 - Parsing of {} broken; breaks startup scripts
• BZ - 463880 - bash completion in UTF8 locale has cursor positioning errors with long $PS1
• BZ - 475474 - CVE-2008-5374 bash: Insecure temporary file use in aliasconv.sh, aliasconv.bash, cshtobash (symlink attack)
• BZ - 484809 - [RHEL5] bash includes Control-D in "bad ELF interpreter" message
• BZ - 492908 - $RANDOM value remains the same
• BZ - 503701 - Cannot process scripts beyond an embedded NULL character when running in 'source' mode
• BZ - 504904 - trap -p not displaying ignored signal when run from child bash
• BZ - 525474 - bash/readline not detecting window resize properly
• BZ - 583919 - tab-completion appends slash to non-directories
• BZ - 592979 - system global bash.bash_logout is diabled in config-top.h
• BZ - 618393 - memory leak in bash reading files
• BZ - 663656 - Unusable loadables in /doc

CVEs

• CVE-2008-5374

References

• https://access.redhat.com/security/updates/classification/#low