The __sys_sendmsg function in net/socket.c in the Linux kernel before 3.1 allows local users to cause a denial of service (system crash) via crafted use of the sendmmsg system call, leading to an incorrect pointer dereference.
https://github.com/torvalds/linux/commit/bc909d9ddbf7778371e36a651d6e4194b1cc7d4c
https://bugzilla.redhat.com/show_bug.cgi?id=761646
http://www.openwall.com/lists/oss-security/2011/12/08/4