RedHat Enterprise Linux 4: RHSA-2008:0237-01 Critical Kernel Update for DoS

The kernel packages contain the Linux kernel, the core of any Linux operating system.
These updated packages fix the following security issues:
* the absence of a protection mechanism when attempting to access a critical section of code has been found in the Linux kernel open file descriptors control mechanism, fcntl. This could allow a local unprivileged user to simultaneously execute code, which would otherwise be protected against parallel execution. As well, a race condition when handling locks in the Linux kernel fcntl functionality, may have allowed a process belonging to a local unprivileged user to gain re-ordered access to the descriptor table. (CVE-2008-1669, Important)
* on AMD64 architectures, the possibility of a kernel crash was discovered by testing the Linux kernel process-trace ability. This could allow a local unprivileged user to cause a denial of service (kernel crash). (CVE-2008-1615, Important)
* the absence of a protection mechanism when attempting to access a critical section of code, as well as a race condition, have been found in the Linux kernel file system event notifier, dnotify. This could allow a local unprivileged user to get inconsistent data, or to send arbitrary signals to arbitrary system processes. (CVE-2008-1375, Important)
Red Hat would like to thank Nick Piggin for responsibly disclosing the following issue:
* when accessing kernel memory locations, certain Linux kernel drivers registering a fault handler did not perform required range checks. A local unprivileged user could use this flaw to gain read or write access to arbitrary kernel memory, or possibly cause a kernel crash. (CVE-2008-0007, Important)
* the possibility of a kernel crash was found in the Linux kernel IPsec protocol implementation, due to improper handling of fragmented ESP packets. When an attacker controlling an intermediate router fragmented these packets into very small pieces, it would cause a kernel crash on the receiving node during packet reassembly. (CVE-2007-6282, Important)
* a flaw in the MOXA serial driver could allow a local unprivileged user to perform privileged operations, such as replacing firmware. (CVE-2005-0504, Important)
As well, these updated packages fix the following bugs:
* multiple buffer overflows in the neofb driver have been resolved. It was not possible for an unprivileged user to exploit these issues, and as such, they have not been handled as security issues.
* a kernel panic, due to inconsistent detection of AGP aperture size, has been resolved.
* a race condition in UNIX domain sockets may have caused "recv()" to return zero. In clustered configurations, this may have caused unexpected failovers.
* to prevent link storms, network link carrier events were delayed by up to one second, causing unnecessary packet loss. Now, link carrier events are scheduled immediately.
* a client-side race on blocking locks caused large time delays on NFS file systems.
* in certain situations, the libATA sata_nv driver may have sent commands with duplicate tags, which were rejected by SATA devices. This may have caused infinite reboots.
* running the "service network restart" command may have caused networking to fail.
* a bug in NFS caused cached information about directories to be stored for too long, causing wrong attributes to be read.
* on systems with a large highmem/lowmem ratio, NFS write performance may have been very slow when using small files.
* a bug, which caused network hangs when the system clock was wrapped around zero, has been resolved.
Red Hat Enterprise Linux 4 users are advised to upgrade to these updated packages, which contain backported patches to resolve these issues.