The rs_ioctl function in drivers/char/amiserial.c in the Linux kernel 2.6.36.1 and earlier does not properly initialize a certain structure member, which allows local users to obtain potentially sensitive information from kernel stack memory via a TIOCGICOUNT ioctl call.
http://lkml.org/lkml/2010/9/15/389
http://www.openwall.com/lists/oss-security/2010/09/25/2
http://www.openwall.com/lists/oss-security/2010/10/06/6
http://www.openwall.com/lists/oss-security/2010/10/07/1