[NET]: Take dev_base_lock when moving device name hash list entry

When we added name-based hashing the dev_base_lock was designated as the
lock to take when changing the name hash list.  Unfortunately, because
it was a preexisting lock that just happened to be taken in the right
spots we neglected to take it in dev_change_name.

The race can affect calles of __dev_get_by_name that do so without taking
the RTNL.  They may end up walking down the wrong hash chain and end up
missing the device that they're looking for.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 7bfea5e9030e..346cbf66534e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -839,8 +839,12 @@ int dev_change_name(struct net_device *dev, char *newname)
                 strlcpy(dev->name, newname, IFNAMSIZ);
 
         device_rename(&dev->dev, dev->name);
+
+        write_lock_bh(&dev_base_lock);
         hlist_del(&dev->name_hlist);
         hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name));
+        write_unlock_bh(&dev_base_lock);
+
         raw_notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev);
 
         return err;