The kernel packages contain the Linux kernel, the core of any Linux operating system. Security fixes: * a NULL pointer dereference flaw was found in the Linux kernel NFSv4 implementation. Several of the NFSv4 file locking functions failed to check whether a file had been opened on the server before performing locking operations on it. A local, unprivileged user on a system with an NFSv4 share mounted could possibly use this flaw to cause a kernel panic or escalate their privileges. * a flaw was found in the sctp_process_unk_param function in the Linux kernel Stream Control Transmission Protocol implementation. A remote attacker could send a specially-crafted SCTP packet to an SCTP listening port on a target system, causing a kernel panic . * a race condition between finding a keyring by name and destroying a freed keyring was found in the Linux kernel key management facility. A local, unprivileged user could use this flaw to cause a kernel panic or escalate their privileges. Red Hat would like to thank Simon Vallet for responsibly reporting CVE-2009-3726; and Jukka Taimisto and Olli Jarva of Codenomicon Ltd, Nokia Siemens Networks, and Wind River on behalf of their customer, for responsibly reporting CVE-2010-1173. Bug fixes: * RHBA-2007:0791 introduced a regression in the Journaling Block Device . Under certain circumstances, removing a large file did not result in inactive memory being freed, leading to the system having a large amount of inactive memory. Now, the memory is correctly freed. * the timer_interrupt routine did not scale lost real ticks to logical ticks correctly, possibly causing time drift for 64-bit Red Hat Enterprise Linux 4 KVM guests that were booted with the "divider=x" kernel parameter set to a value greater than 1. "warning: many lost ticks" messages may have been logged on the affected guest systems. * a bug could have prevented NFSv3 clients from having the most up-to-date file attributes for files on a given NFSv3 file system. In cases where a file type changed, such as if a file was removed and replaced with a directory of the same name, the NFSv3 client may not have noticed this change until stat was called . * RHBA-2007:0791 introduced bugs in the Linux kernel PCI-X subsystem. These could have caused a system deadlock on some systems where the BIOS set the default Maximum Memory Read Byte Count to 4096, and that also use the Intel PRO/1000 Linux driver, e1000. Errors such as "e1000: eth[x]: e1000_clean_tx_irq: Detected Tx Unit Hang" were logged. * an out of memory condition in a KVM guest, using the virtio-net network driver and also under heavy network stress, could have resulted in that guest being unable to receive network traffic. Users had to manually remove and re-add the virtio_net module and restart the network service before networking worked as expected. Such memory conditions no longer prevent KVM guests receiving network traffic. * when an SFQ qdisc that limited the queue size to two packets was added to a network interface, sending traffic through that interface resulted in a kernel crash. Such a qdisc no longer results in a kernel crash. * when an NFS client opened a file with the O_TRUNC flag set, it received a valid stateid, but did not use that stateid to perform the SETATTR call. Such cases were rejected by Red Hat Enterprise Linux 4 NFS servers with an "NFS4ERR_BAD_STATEID" error, possibly preventing some NFS clients from writing files to an NFS file system. 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.