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CVE-2008-2136

A few days ago I noticed that NFS performance between a web server node and NFS server went down by 50%. NFS was optimized and the only thing was updated Red Hat kernel v5.2. I also noticed same trend on CentOS 5.2 64 bit edition.

NFS server crashed each and every time web server node tried to store a large file 20-100 MB each. Read performance was fine but write performance went to hell. Finally, I had to rollback the updates. Recently, while reading Red Hat site I came across the solution.

Updated kernel packages that fix various security issues and several bugs are now available for Red Hat Enterprise Linux 5:

* a 50-75% drop in NFS server rewrite performance, compared to Red Hat
Enterprise Linux 4.6, has been resolved.

After upgrading kernel on both server and client my issue resolved:
# yum update

Canonical Ltd has issued updates for its Kernel package to plug multiple security holes. A security issue affects the following Ubuntu releases:

=> Ubuntu 6.06 LTS
=> Ubuntu 7.04
=> Ubuntu 7.10
=> Ubuntu 8.04 LTS

This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu.

Description

IPsec protocol stack did not correctly handle fragmented ESP packets. A remote attacker could exploit this to crash the system, leading to a denial of service.(CVE-2007-6282)

The 64bit kernel did not correctly handle hrtimer updates. A local attacker could request a large expiration value and cause the system to hang, leading to a denial of service. (CVE-2007-6712)

The ia32 emulation under 64bit kernels did not fully clear uninitialized data. A local attacker could read private kernel memory, leading to a loss of privacy. (CVE-2008-0598)

A race condition was discovered between ptrace and utrace in the kernel. A
local attacker could exploit this to crash the system, leading to a denial
of service. (CVE-2008-2365)

The copy_to_user routine in the kernel did not correctly clear memory destination addresses when running on 64bit kernels. A local attacker could exploit this to gain access to sensitive kernel memory, leading to a loss of privacy. (CVE-2008-2729)

The PPP over L2TP routines in the kernel did not correctly handle certain messages. A remote attacker could send a specially crafted packet that could crash the system or execute arbitrary code. (CVE-2008-2750)

Gabriel Campana discovered that SCTP routines did not correctly check for large addresses. A local user could exploit this to allocate all available memory, leading to a denial of service. (CVE-2008-2826)

How do I update Kernel package?

Open terminal and type the following two commands:
$ sudo apt-get update
$ sudo apt-get upgrade

After a standard system upgrade you need to reboot your computer to effect the necessary changes:
$ sudo reboot