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7.12. autofs

Updated autofs packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 6.
Red Hat Product Security has rated this update as having Moderate 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.
The autofs utility controls the operation of the automount daemon. The daemon automatically mounts file systems when in use and unmounts them when they are not busy.

Security Fix

It was found that program-based automounter maps that used interpreted languages such as Python would use standard environment variables to locate and load modules of those languages. A local attacker could potentially use this flaw to escalate their privileges on the system.


This issue has been fixed by adding the "AUTOFS_" prefix to the affected environment variables so that they are not used to subvert the system. A configuration option ("force_standard_program_map_env") to override this prefix and to use the environment variables without the prefix has been added. In addition, warnings have been added to the manual page and to the installed configuration file. Now, by default the standard variables of the program map are provided only with the prefix added to its name.
Red Hat would like to thank the Georgia Institute of Technology for reporting this issue.

Bug Fixes

If the "ls *" command was executed before a valid mount, the autofs program failed on further mount attempts inside the mount point, whether the mount point was valid or not. While attempting to mount, the "ls *" command of the root directory of an indirect mount was executed, which led to an attempt to mount "*", causing it to be added to the negative map entry cache. This bug has been fixed by checking for and not adding "*" while updating the negative map entry cache.
The autofs program by design did not mount host map entries that were duplicate exports in an NFS server export list. The duplicate entries in a multi-mount map entry were recognized as a syntax error and autofs refused to perform mounts when the duplicate entries occurred. Now, autofs has been changed to continue mounting the last seen instance of the duplicate entry rather than fail, and to report the problem in the log files to alert the system administrator.
The autofs program did not recognize the yp map type in the master map. This was caused by another change in the master map parser to fix a problem with detecting the map format associated with mapping the type in the master map. The change led to an incorrect length for the type comparison of yp maps that resulted in a match operation failure. This bug has been fixed by correcting the length which is used for the comparison.
The autofs program did not update the export list of the Sun-format maps of the network shares exported from an NFS server. This happened due to a change of the Sun-format map parser leading to the hosts map update to stop working on the map re-read operation. The bug has been now fixed by selectively preventing this type of update only for the Sun-formatted maps. The updates of the export list on the Sun-format maps are now visible and refreshing of the export list is no longer supported for the Sun-formatted hosts map.
Within changes made for adding of the Sun-format maps, an incorrect check was added that caused a segmentation fault in the Sun-format map parser in certain circumstances. This has been now fixed by analyzing the intent of the incorrect check and changing it in order to properly identify the conditions without causing a fault.
A bug in the autofs program map lookup module caused an incorrect map format type comparison. The incorrect comparison affected the Sun-format program maps where it led to the unused macro definitions. The bug in the comparison has been fixed so that the macro definitions are not present for the Sun-format program maps.
Users of autofs are advised to upgrade to these updated packages, which contain backported patches to correct these issues.