RDMA/cma: Fix initialization of next_port

next_port should be between sysctl_local_port_range[0] and [1].
However, it is initially set to a random value with get_random_bytes().  
If the value is negative when treated as a signed integer, next_port
can end up outside the expected range because of the result of the % 
operator being negative.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 2eb52b7a71da..32a0e66d2a23 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2773,8 +2773,8 @@ static int cma_init(void)
         int ret;
 
         get_random_bytes(&next_port, sizeof next_port);
-        next_port = (next_port % (sysctl_local_port_range[1] -
-                                  sysctl_local_port_range[0])) +
+        next_port = ((unsigned int) next_port %
+                    (sysctl_local_port_range[1] - sysctl_local_port_range[0])) +
                     sysctl_local_port_range[0];
         cma_wq = create_singlethread_workqueue("rdma_cm");
         if (!cma_wq)