RHBA-2015:0300 - Bug Fix Advisory

Topic

Updated ksh packages that fix several bugs are now available for Red Hat
Enterprise Linux 7.

Description

KornShell (KSH) is a Unix shell developed by AT&T Bell Laboratories, which is
backward-compatible with the Bourne shell (Bash) and includes many features of
the C shell. The most recent version is KSH-93. KornShell complies with the
POSIX.2 standard (IEEE Std 1003.2-1992).

This update fixes the following bugs:

• Prior to this update, the compiler optimization dropped parts from the ksh job

locking mechanism from the binary code. As a consequence, ksh could terminate
unexpectedly with a segmentation fault after it received the SIGCHLD signal.
This update implements a fix to ensure the compiler does not drop parts of the
ksh mechanism, and the crash no longer occurs. (BZ#1116506)

• When running a command that output a lot of data, and then setting a variable

from that output, ksh could become unresponsive. The combination of I/O
redirection and synchronization mechanism has been changed, and, as a result,
commands complete successfully, and ksh no longer hangs. (BZ#1077090)

• Due to a race condition in the job list code, ksh could terminate

unexpectedly with a segmentation fault when the user had run custom scripts on
their system. With this update, the race condition has been fixed, and
segmentation faults in ksh no longer occur. (BZ#1084406)

• Previously, ksh did not check whether it had execution permission

for a directory before changing into it. Consequently, ksh erroneously supposed
that it was operating inside that directory even though it was in fact still
operating in the previous directory. With this update, ksh checks for execute
permissions and, if lacking them, reports an error message as expected.
(BZ#1109893)

• Previously, ksh reused low file descriptor numbers, when any of them

were previously closed, but did not handle them correctly when they were not
used for standard input, output or error output. As a result, when any of
standard input (stdin), output (stdout) or error (stderr) was closed and its
file descriptor was reused in command substitution, the output from command
substitution was empty. The code was updated to not reuse those low file
descriptors for command substitution. Command substitution now works correctly
even if any of stdin, stdout or stderr
is closed. (BZ#1133585)

• Previously, ksh could incorrectly initialize a variable holding the path of

the working directory. If a program changed the working directory between
forking and ksh execution, then ksh could contain a incorrect value in the
working directory variable. With this update, initialization of the working
directory variable has been corrected, and ksh now contains the correct value in
the aforementioned situation. (BZ#1135573)

• Previously, the ksh syntax analyser did not parse command substitutions inside

of here-documents correctly, which led to syntax error messages being reported
on a syntactically-correct code. A patch has been provided to fix this bug, and
ksh now interprets substitutes as intended. (BZ#1111120)

• Previously, ksh could skip setting the exit code from the last command of a

function. As a consequence, the function could return a incorrect exit code. The
ksh code has been updated to use the latest command of a function, and functions
thus return correct exit code. (BZ#1146507)

• Previously, if a running function was unset by another function in the ksh

script, the ksh shell terminated unexpectedly with a segmentation fault. With
this update, the ksh code skips resetting the "running" flag if a function is
unset, and ksh no longer crashes in the described scenario. (BZ#1105153)

• Previously, ksh truncated too many decimals before rounding for numbers

smaller than one. As a consequence, numbers from the interval of 0.5 - 0.999
were incorrectly rounded to zero. This update ensures that there are always
enough decimals for correct rounding, and the result of rounding is now correct.
(BZ#1070871)

Users of ksh are advised to upgrade to these updated packages, which fix these
bugs.

Solution

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

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux Server from RHUI 7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 s390x
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 ppc64

Fixes

• BZ - 1085385 - ksh exit produces "Interrupt (core dumped)"
• BZ - 1100215 - ksh monitor mode documented contrary to what it actually does
• BZ - 1109893 - RHEL7: ksh not giving error on "cd" to directory without execute bit
• BZ - 1133585 - broken command substitution while stdout closed
• BZ - 1135573 - ksh: Problem with 'cd' from a forked C program
• BZ - 1141243 - shell hangs if setting variable from command that produces more than 120k and is piped
• BZ - 1146161 - korn shell installation does not include symlink for the restricted shell

CVEs

(none)

References

(none)