CVE-2021-47559

In the Linux kernel, the following vulnerability has been resolved:
net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk() Coverity
reports a possible NULL dereferencing problem: in smc_vlan_by_tcpsk(): 6.
returned_null: netdev_lower_get_next returns NULL (checked 29 out of 30
times). 7. var_assigned: Assigning: ndev = NULL return value from
netdev_lower_get_next. 1623 ndev = (struct net_device
*)netdev_lower_get_next(ndev, &lower); CID 1468509 (#1 of 1): Dereference
null return value (NULL_RETURNS) 8. dereference: Dereferencing a pointer
that might be NULL ndev when calling is_vlan_dev. 1624 if
(is_vlan_dev(ndev)) { Remove the manual implementation and use
netdev_walk_all_lower_dev() to iterate over the lower devices. While on it
remove an obsolete function parameter comment.