RHBA-2014:0362 - Bug Fix Advisory

Topic

Updated kernel packages that fix several bugs are now available for Red Hat
Enterprise Linux 6.2 Long Life.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating
system.

This update fixes the following bugs:

• Due to a bug in ext4 metadata allocation code, the number of metadata blocks

needed to complete a file system operation could be calculated incorrectly.
Consequently, when performing file system operations on a nearly full ext4 file
system, unexpected allocation failures could occur at writeback time, leading to
possible data loss and file system inconsistency. A series of patches has been
applied, fixing metadata allocation estimation problems and introducing a
reserved space concept that ensures correct allocation of metadata in specific
situations, such as the aforementioned scenario. (BZ#1059380)

• Previously, the sysfs_dev_char_kobj variable was freed on shutdown, but the

variable could be used later by the USB stack, and possibly other code, which
could cause the system to terminate unexpectedly. The underlying source code has
been modified to prevent "kobjects" in the device_shutdown() function from being
removed, as the /sys/dev/block/ and /sys/dev/char/ directories must be kept
because of the symbolic links pointing to the devices. As a result, the system
no longer crashes in the described scenario. (BZ#1063349)

• Due to an incorrect call of the weak-modules script in the kernel spec file,

weak-modules was removed from the system when removing or upgrading certain
kernel packages related to weak-modules, such as kernel-debug. With this update,
the the weak-modules call in the kernel spec file has been corrected, and the
script now preserves on the system as expected in this scenario. (BZ#1076598)

• Due to several bugs in the ext4 code, data integrity system calls did not

always properly persist data on the disk. Therefore, the unsynchronized data in
the ext4 file system could have been lost after the system's unexpected
termination. A series of patches has been applied to the ext4 code to address
this problem, including a fix that ensures proper usage of data barriers in the
code responsible for file synchronization. Data loss no longer occurs in the
described situation. (BZ#1064965)

• A bug in the journaling block device (jbd and jbd2) code could, under certain

circumstances, trigger a BUG_ON() assertion and result in a kernel oops. This
happened when an application performed an extensive number of commits to the
journal of the ext3 file system and there was no currently active transaction
while synchronizing the file's in-core state. This problem has been resolved by
correcting respective test conditions in the jbd and jbd2 code. (BZ#1066323)

All users are advised to upgrade to these updated packages, which contain
backported patches to correct these bugs. The system must be rebooted for this
update to take effect.

Solution

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

To install kernel packages manually, use "rpm -ivh [package]". Do not use
"rpm -Uvh" as that will remove the running kernel binaries from your
system. You may use "rpm -e" to remove old kernels after determining that
the new kernel functions properly on your system.

Affected Products

• Red Hat Enterprise Linux Server - AUS 6.2 x86_64

Fixes

CVEs

(none)

References

(none)