Security Advisory Moderate: gfs-kmod security, bug fix and enhancement update

Advisory: RHSA-2010:0291-4
Type: Security Advisory
Severity: Moderate
Issued on: 2010-03-30
Last updated on: 2010-03-30
Affected Products: RHEL Cluster-Storage (v. 5 server)
CVEs ( CVE-2010-0727


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.

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.


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

Updated packages

RHEL Cluster-Storage (v. 5 server)

File outdated by:  RHBA-2014:1234
    MD5: b1c2bb692ba19f4ebe8fa576a9ad9fcf
SHA-256: b2d0f93451cb54952d0721d89b5b3f0299de268c33119965230e4b7ecb82bc19
File outdated by:  RHBA-2014:1234
    MD5: d7f39d441cdafa69022717792be87797
SHA-256: 9e7576fd8e1b29890a92c0523ac756e5ee3f1b18928c78aabc812ec6624cc7b7
File outdated by:  RHBA-2014:1234
    MD5: 5b194b008ee2140716c141b6a753663d
SHA-256: 791aa9ed2f6f0a86f38635f5f39233da671d34083538c39206cbdd2fcb338cc1
File outdated by:  RHBA-2014:1234
    MD5: d7ace4355a701f044ca5184d2cc6ee27
SHA-256: 27c6f10d5a8bc39249eba12e35e5948c997357a0931810f8a9991d154559eaf1
File outdated by:  RHBA-2014:1234
    MD5: 4be4fe589ed794ebb9ff3c5e33accb15
SHA-256: 9c23a4e6454fd8e351670a22297ab9cd1ba28e5f6f7d6ec22a26c19302d3aba7
File outdated by:  RHBA-2014:1234
    MD5: c0537f35b10b89457c8708d2b3986626
SHA-256: aee3dd6856bba995f589fc1d5a867765d28fe2b1c92e2a0c02a50c3ee4e9d8f2
File outdated by:  RHBA-2014:1234
    MD5: 7fbfdb9a25ce87ae19e0362f451a356b
SHA-256: 879ca6c292ea399d0925d9d049154570fb9e39c27a0b92315bfbf0a96bcb0b92
File outdated by:  RHBA-2014:1234
    MD5: 1b24a8dc1e3d8e17a625407072fb5b3e
SHA-256: 654cf89fe5729078f865358f83b76b036cf17435c7826daa5343b0e18b685854
File outdated by:  RHBA-2014:1234
    MD5: 9573470a805a8d14c4f27a7ecede47d7
SHA-256: 83f1bdce69f52a033cc501c43063d173c7254864676112d45c99ebcca9d48fb8
(The unlinked packages above are only available from the Red Hat Network)

Bugs fixed (see bugzilla for more information)

471258 - fatal: assertion "gfs_glock_is_locked_by_me(gl) && gfs_glock_is_held_excl(gl)" failed
487610 - GFS: Change gfs freeze/unfreeze to use new standard
513885 - GFS kernel panic, suid + nfsd with posix ACLs enabled
515717 - Flock on GFS fs file will error with "Resource tempory unavailable" for EWOULDBLOCK
517145 - [RFE] GFS: New mount option: -o errors=withdraw|panic
570863 - CVE-2010-0727 bug in GFS/GFS2 locking code leads to dos


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