[PATCH 3.16 049/294] IB/cma: Fix reference count leak when no ipv4 addresses are set

[Ben Hutchings]

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

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

From: "Kalderon, Michal" <Michal.Kalderon@xxxxxxxxxx>

commit 963916fdb3e5ad4af57ac959b5a03bf23f7568ca upstream.

Once in_dev_get is called to receive in_device pointer, the
in_device reference counter is increased, but if there are
no ipv4 addresses configured on the net-device the ifa_list
will be null, resulting in a flow that doesn't call in_dev_put
to decrease the ref_cnt.
This was exposed when running RoCE over ipv6 without any ipv4
addresses configured

Fixes: commit 8e3867310c90 ("IB/cma: Fix a race condition in iboe_addr_get_sgid()")

Signed-off-by: Michal Kalderon <Michal.Kalderon@xxxxxxxxxx>
Signed-off-by: Ariel Elior <Ariel.Elior@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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
@@ -185,11 +185,13 @@ static inline void iboe_addr_get_sgid(st
 	dev = dev_get_by_index(&init_net, dev_addr->bound_dev_if);
 	if (dev) {
 		ip4 = in_dev_get(dev);
-		if (ip4 && ip4->ifa_list && ip4->ifa_list->ifa_address) {
+		if (ip4 && ip4->ifa_list && ip4->ifa_list->ifa_address)
 			ipv6_addr_set_v4mapped(ip4->ifa_list->ifa_address,
 					       (struct in6_addr *)gid);
+
+		if (ip4)
 			in_dev_put(ip4);
-		}
+
 		dev_put(dev);
 	}
 }