Updated kernel packages that fix one security issue and multiple bugs are now available for Red Hat Enterprise Linux 5. The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System base score, which gives a detailed severity rating, is available from the CVE link in the References section. The kernel packages contain the Linux kernel, the core of any Linux operating system. This update fixes the following security issue: * A flaw was found in the way the Xen hypervisor AMD IOMMU driver handled interrupt remapping entries. By default, a single interrupt remapping table is used, and old interrupt remapping entries are not cleared, potentially allowing a privileged guest user in a guest that has a passed-through, bus-mastering capable PCI device to inject interrupt entries into others guests, including the privileged management domain , leading to a denial of service. Red Hat would like to thank the Xen project for reporting the CVE-2013-0153 issue. This update also fixes the following bugs: * When a process is opening a file over NFSv4, sometimes an OPEN call can succeed while the following GETATTR operation fails with an NFS4ERR_DELAY error. The NFSv4 code did not handle such a situation correctly and allowed an NFSv4 client to attempt to use the buffer that should contain the GETATTR information. However, the buffer did not contain the valid GETATTR information, which caused the client to return a "-ENOTDIR" error. Consequently, the process failed to open the requested file. This update backports a patch that adds a test condition verifying validity of the GETATTR information. If the GETATTR information is invalid, it is obtained later and the process opens the requested file as expected. * Previously, the xdr routines in NFS version 2 and 3 conditionally updated the res->count variable. Read retry attempts after a short NFS read call could fail to update the res->count variable, resulting in truncated read data being returned. With this update, the res->count variable is updated unconditionally so this bug can no longer occur. * When handling requests from Intelligent Platform Management Interface clients, the IPMI driver previously used two different locks for an IPMI request. If two IPMI clients sent their requests at the same time, each request could receive one of the locks and then wait for the second lock to become available. This resulted in a deadlock situation and the system became unresponsive. The problem could occur more likely in environments with many IPMI clients. This update modifies the IPMI driver to handle the received messages using tasklets so the driver now uses a safe locking technique when handling IPMI requests and the mentioned deadlock can no longer occur. * Incorrect locking around the cl_state_owners list could cause the NFSv4 state reclaimer thread to enter an infinite loop while holding the Big Kernel Lock . As a consequence, the NFSv4 client became unresponsive. With this update, safe list iteration is used, which prevents the NFSv4 client from hanging in this scenario. Users should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.