[NETNS]: Double free in netlink_release.
Netlink protocol table is global for all namespaces. Some netlink
protocols have been virtualized, i.e. they have per/namespace netlink
socket. This difference can easily lead to double free if more than 1
namespace is started. Count the number of kernel netlink sockets to
track that this table is not used any more.
Signed-off-by: Denis V. Lunev <email@example.com>
Tested-by: Alexey Dobriyan <firstname.lastname@example.org>
Signed-off-by: David S. Miller <email@example.com>
(cherry picked from commit 869e58f87094b1e8a0df49232e4a5172678d46c9)