1.61. gfs-kmod

Updated gfs-kmod packages that fix one security issue, numerous bugs, and add one enhancement are now available for Red Hat Enterprise Linux 5.5, kernel release 2.6.18-194.el5.

The Red Hat Security Response Team 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 gfs-kmod packages contain modules that provide the ability to mount and use GFS file systems.

A flaw was found in the gfs_lock() implementation. The GFS locking code could skip the lock operation for files that have the S_ISGID bit (set-group-ID on execution) in their mode set. A local, unprivileged user on a system that has a GFS file system mounted could use this flaw to cause a kernel panic. (CVE-2010-0727)

These updated gfs-kmod packages are in sync with the latest kernel (2.6.18-194.el5). The modules in earlier gfs-kmod packages failed to load because they did not match the running kernel. It was possible to force-load the modules. With this update, however, users no longer need to.

These updated gfs-kmod packages also fix the following bugs:

* when SELinux was in permissive mode, a race condition during file creation could have caused one or more cluster nodes to be fenced and lock the remaining nodes out of the GFS file system. This race condition no longer occurs with this update. (BZ#471258)

* when ACLs (Access Control Lists) are enabled on a GFS file system, if a transaction that has started to do a write request does not have enough spare blocks for the operation it causes a kernel panic. This update ensures that there are enough blocks for the write request before starting the operation. (BZ#513885)

* requesting a "flock" on a file in GFS in either read-only or read-write mode would sometimes cause a "Resource temporarily unavailable" state error (error 11 for EWOULDBLOCK) to occur. In these cases, a flock could not be obtained on the file in question. This has been fixed with this update so that flocks can successfully be obtained on GFS files without this error occurring. (BZ#515717)

* the GFS withdraw function is a data integrity feature of GFS file systems in a cluster. If the GFS kernel module detects an inconsistency in a GFS file system following an I/O operation, the file system becomes unavailable to the cluster. The GFS withdraw function is less severe than a kernel panic, which would cause another node to fence the node. With this update, you can override the GFS withdraw function by mounting the file system with the "-o errors=panic" option specified. When this option is specified, any errors that would normally cause the system to withdraw cause the system to panic instead. This stops the node's cluster communications, which causes the node to be fenced. (BZ#517145)

Finally, these updated gfs-kmod packages provide the following enhancement:

* the GFS kernel modules have been updated to use the new generic freeze and unfreeze ioctl interface that is also supported by the following file systems: ext3, ext4, GFS2, JFS and ReiserFS. With this update, GFS supports freeze/unfreeze through the VFS-level FIFREEZE/FITHAW ioctl interface. (BZ#487610)

Users are advised to upgrade to these latest gfs-kmod packages, updated for use with the 2.6.18-194.el5 kernel, which contain backported patches to correct these issues, fix these bugs, and add this enhancement.