[PATCH 4.8 69/96] IB/cma: Fix a race condition in iboe_addr_get_sgid()

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanass...@sandisk.com>

commit fba332b079029c2f4f7e84c1c1cd8e3867310c90 upstream.

Code that dereferences the struct net_device ip_ptr member must be
protected with an in_dev_get() / in_dev_put() pair. Hence insert
calls to these functions.

Fixes: commit 7b85627b9f02 ("IB/cma: IBoE (RoCE) IP-based GID addressing")
Signed-off-by: Bart Van Assche <bart.vanass...@sandisk.com>
Reviewed-by: Moni Shoua <mo...@mellanox.com>
Cc: Or Gerlitz <ogerl...@mellanox.com>
Cc: Roland Dreier <rol...@purestorage.com>
Signed-off-by: Doug Ledford <dledf...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 include/rdma/ib_addr.h |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/include/rdma/ib_addr.h
+++ b/include/rdma/ib_addr.h
@@ -205,10 +205,12 @@ static inline void iboe_addr_get_sgid(st
 
        dev = dev_get_by_index(&init_net, dev_addr->bound_dev_if);
        if (dev) {
-               ip4 = (struct in_device *)dev->ip_ptr;
-               if (ip4 && ip4->ifa_list && ip4->ifa_list->ifa_address)
+               ip4 = in_dev_get(dev);
+               if (ip4 && ip4->ifa_list && ip4->ifa_list->ifa_address) {
                        ipv6_addr_set_v4mapped(ip4->ifa_list->ifa_address,
                                               (struct in6_addr *)gid);
+                       in_dev_put(ip4);
+               }
                dev_put(dev);
        }
 }