The kernel packages contain the Linux kernel, the core of any Linux operating system. * A NULL pointer dereference flaw was found in the rds_iw_laddr_check function in the Linux kernel"s implementation of Reliable Datagram Sockets . A local, unprivileged user could use this flaw to crash the system. * It was found that the Xen hypervisor implementation did not properly clean memory pages previously allocated by the hypervisor. A privileged guest user could potentially use this flaw to read data relating to other guests or the hypervisor itself. Red Hat would like to thank the Xen project for reporting CVE-2014-4021. Upstream acknowledges Jan Beulich as the original reporter. This update also fixes the following bugs: * A bug in the journaling block device 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. * After a statically defined gateway became unreachable and its corresponding neighbor entry entered a FAILED state, the gateway stayed in the FAILED state even after it became reachable again. As a consequence, traffic was not routed through that gateway. This update allows probing such a gateway automatically so that the traffic can be routed through this gateway again once it becomes reachable. * Due to an incorrect condition check in the IPv6 code, the ipv6 driver was unable to correctly assemble incoming packet fragments, which resulted in a high IPv6 packet loss rate. This update fixes the said check for a fragment overlap and ensures that incoming IPv6 packet fragments are now processed as expected. * Recent changes in the d_splice_alias function introduced a bug that allowed d_splice_alias to return a dentry from a different directory than the directory being looked up. As a consequence in cluster environment, a kernel panic could be triggered when a directory was being removed while a concurrent cross-directory operation was performed on this directory on another cluster node. This update avoids the kernel panic in this situation by correcting the search logic in the d_splice_alias function so that the function can no longer return a dentry from an incorrect directory. * The NFSv4 server did not handle multiple OPEN operations to the same file separately, which could cause the NFSv4 client to repeatedly send CLOSE requests with the same state ID, even though the NFS server rejected the request with an NFS4ERR_OLD_STATEID error code. This update ensures that the NFSv4 client no longer re-sends the same CLOSE request after receiving NFS4ERR_OLD_STATEID. All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.