RHSA-2010:0291: Moderate: gfs-kmod security, bug fix and enhancement update

The gfs-kmod packages contain modules that provide the ability to mount anduse GFS file systems.A flaw was found in the gfslock() implementation. The GFS locking codecould skip the lock operation for files that have the SISGID bit(set-group-ID on execution) in their mode set. A local, unprivileged useron a system that has a GFS file system mounted could use this flaw to causea 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 loadbecause they did not match the running kernel. It was possible toforce-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 lockthe remaining nodes out of the GFS file system. This race condition nolonger 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 enoughspare blocks for the operation it causes a kernel panic. This updateensures that there are enough blocks for the write request before startingthe 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 beobtained on the file in question. This has been fixed with this update sothat flocks can successfully be obtained on GFS files without this erroroccurring. (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 GFSfile system following an I/O operation, the file system becomes unavailableto the cluster. The GFS withdraw function is less severe than a kernelpanic, which would cause another node to fence the node. With this update,you can override the GFS withdraw function by mounting the file system withthe "-o errors=panic" option specified. When this option is specified, anyerrors that would normally cause the system to withdraw cause the system topanic instead. This stops the node's cluster communications, which causesthe 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 filesystems: ext3, ext4, GFS2, JFS and ReiserFS. With this update, GFS supportsfreeze/unfreeze through the VFS-level FIFREEZE/FITHAW ioctl interface.(BZ#487610)Users are advised to upgrade to these latest gfs-kmod packages, updated foruse with the 2.6.18-194.el5 kernel, which contain backported patches tocorrect these issues, fix these bugs, and add this enhancement.