Description of problem: On parsing malformed X.25 facilities, decrementing the remaining length may cause it to underflow. Since the length is an unsigned integer, this will result in the loop continuing until the kernel crashes.
This patch adds checks to ensure decrementing the remaining length does not cause it to wrap around.
http://marc.info/?l=linux-netdev&m=128951543005554&w=2
Acknowledgements:
Red Hat would like to thank Dan Rosenberg for reporting this issue.
Statement:
This issue did not affect the versions of Linux kernel as shipped with Red Hat Enterprise Linux 4, 5, 6 and Red Hat Enterprise MRG as they did not include support for CCITT X.25 Packet Layer.
Memory leak in the appletalk subsystem in the Linux kernel 2.4.x through 2.4.37.6 and 2.6.x through 2.6.31, when the appletalk and ipddp modules are loaded but the ipddp"N" device is not found, allows remote attackers to cause a denial of service (memory consumption) via IP-DDP datagrams.
An exploit was posted to full-disclosure labelled "Apache Killer". This script creates a number of threads that use multiple Range headers to exhaust memory on the Apache server.
The ASF httpd development team are working on a fix for this issue: http://www.gossamer-threads.com/lists/apache/dev/401638