rds: Integer overflow in RDS cmsg handling

commit 218854af84038d828a32f061858b1902ed2beec6 upstream.

In rds_cmsg_rdma_args(), the user-provided args->nr_local value is
restricted to less than UINT_MAX.  This seems to need 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.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/rds/rdma.c b/net/rds/rdma.c
index 5ce9437cad672168825e78f43fb1fe38e8ce2b20..cf0dfa77fb7ef2e0d3accd11e327f0a9aa4d4ff3 100644 (file)
--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -472,7 +472,7 @@ static struct rds_rdma_op *rds_rdma_prepare(struct rds_sock *rs,
                goto out;
        }
 
-       if (args->nr_local > (u64)UINT_MAX) {
+       if (args->nr_local > UIO_MAXIOV) {
                ret = -EMSGSIZE;
                goto out;
        }