[PATCH net] net: fix sysfs symlinks of adjacent devices

[Alexander Fomichev <git.user@gmail.com>]

From: "Alexander Y. Fomichev" <git.user@gmail.com>

__netdev_adjacent_dev_insert may add adjacent device from another
namespace. Without proper check it leads to emergence of broken
symlink from/to device not existing in current namespace.
Fix: check net_ns is the same before netdev_adjacent_sysfs_add/del
related to: 4c75431ac3520631f1d9e74aa88407e6374dbbc4

Signed-off-by: Alexander Y. Fomichev <git.user@gmail.com>
---
 net/core/dev.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index ab9a16530c36..887784b2dcde 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4841,7 +4841,8 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
 	pr_debug("dev_hold for %s, because of link added from %s to %s\n",
 		 adj_dev->name, dev->name, adj_dev->name);
 
-	if (netdev_adjacent_is_neigh_list(dev, dev_list)) {
+	if (netdev_adjacent_is_neigh_list(dev, dev_list) &&
+	    net_eq(dev_net(dev), dev_net(adj_dev))) {
 		ret = netdev_adjacent_sysfs_add(dev, adj_dev, dev_list);
 		if (ret)
 			goto free_adj;
@@ -4862,7 +4863,8 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
 	return 0;
 
 remove_symlinks:
-	if (netdev_adjacent_is_neigh_list(dev, dev_list))
+	if (netdev_adjacent_is_neigh_list(dev, dev_list) &&
+	    net_eq(dev_net(dev), dev_net(adj_dev)))
 		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 free_adj:
 	kfree(adj);
-- 
2.1.0