[PATCH 3.16 194/233] IB/ipoib: Fix memory leak in create child syscall

[Ben Hutchings]

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

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

From: Feras Daoud <ferasda@xxxxxxxxxxxx>

commit 4542d66bb26f2d021c70a78e46f183c6675fc4c9 upstream.

The flow of creating a new child goes through ipoib_vlan_add
which allocates a new interface and checks the rtnl_lock.

If the lock is taken, restart_syscall will be called to restart
the system call again. In this case we are not releasing the
already allocated interface, causing a leak.

Fixes: 9baa0b036410 ("IB/ipoib: Add rtnl_link_ops support")
Signed-off-by: Feras Daoud <ferasda@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -133,13 +133,14 @@ int ipoib_vlan_add(struct net_device *pd
 
 	snprintf(intf_name, sizeof intf_name, "%s.%04x",
 		 ppriv->dev->name, pkey);
-	priv = ipoib_intf_alloc(intf_name);
-	if (!priv)
-		return -ENOMEM;
 
 	if (!rtnl_trylock())
 		return restart_syscall();
 
+	priv = ipoib_intf_alloc(intf_name);
+	if (!priv)
+		return -ENOMEM;
+
 	down_write(&ppriv->vlan_rwsem);
 
 	/*