bpf: devmap: fix wrong interface selection in notifier_call

The dev_map_notification() removes interface in devmap if unregistering interface's ifindex is same.
But only checking ifindex is not enough because other netns can have same ifindex. so that wrong interface selection could occurred. Hence netdev pointer comparison code is added.

v2: compare netdev pointer instead of using net_eq() (Daniel Borkmann)
v1: Initial patch

Fixes 2ddf71e23cc2 ("net: add notifier hooks for devmap bpf map")

Signed-off-by Taehee Yoo <[email protected]>

---
 kernel/bpf/devmap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

kernel/bpf/devmap.c +1 -3

index 141710b82a6c..191b79948424 100644
@@ -512,8 +512,7 @@ static int dev_map_notification(struct notifier_block *notifier,
                                struct bpf_dtab_netdev *dev, *odev;
 
                                dev = READ_ONCE(dtab->netdev_map[i]);
-                               if (!dev ||
-                                   dev->dev->ifindex != netdev->ifindex)
+                               if (!dev || netdev != dev->dev)
                                        continue;
                                odev = cmpxchg(&dtab->netdev_map[i], dev, NULL);
                                if (dev == odev)
--

2.17.1

The dev_map_notification() removes interface in devmap if unregistering interface's ifindex is same.
But only checking ifindex is not enough because other netns can have same ifindex. so that wrong interface selection could occurred. Hence netdev pointer comparison code is added.

v2: compare netdev pointer instead of using net_eq() (Daniel Borkmann)
v1: Initial patch

Fixes 2ddf71e23cc2 ("net: add notifier hooks for devmap bpf map")

Signed-off-by Taehee Yoo <[email protected]>