The agp_generic_remove_memory function in drivers/char/agp/generic.c in the Linux kernel before 2.6.38.5 does not validate a certain start parameter, which allows local users to gain privileges or cause a denial of service (system crash) via a crafted AGPIOC_UNBIND agp_ioctl ioctl call, a different vulnerability than CVE-2011-1745.
https://lkml.org/lkml/2011/4/14/293
https://bugzilla.redhat.com/show_bug.cgi?id=698996
http://www.securityfocus.com/bid/47843
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.38.5
http://rhn.redhat.com/errata/RHSA-2011-0927.html
http://openwall.com/lists/oss-security/2011/04/22/7