CVE request: kernel: integer overflow in RDS

[Dan Rosenberg <dan.j.rosenberg () gmail com>]

In rds_cmsg_rdma_args(), the user-provided args->nr_local value is
restricted to less than UINT_MAX.  This needs a tighter upper bound,
since the calculation of total iov_size can overflow, resulting in a
small sock_kmalloc() allocation.  This would probably just result in
walking off the heap and crashing when calling rds_rdma_pages() with a
high count value.  If it somehow doesn't crash here, then memory
corruption could occur soon after.

This is closely related to CVE-2010-3865
(http://www.spinics.net/lists/netdev/msg145359.html), which also
concerned various integer overflow and memory corruption issues in
rds_cmsg_rdma_args().  In fact, I'd say it's due to an incomplete fix.

Reference:
http://marc.info/?l=linux-netdev&m=129001184803080&w=2

-Dan