net: avoid UAF on deleted altname
Jakub Kicinski authored
Altnames are accessed under RCU (dev_get_by_name_rcu())
but freed by kfree() with no synchronization point.

Each node has one or two allocations (node and a variable-size
name, sometimes the name is netdev->name). Adding rcu_heads
here is a bit tedious. Besides most code which unlists the names
already has rcu barriers - so take the simpler approach of adding
synchronize_rcu(). Note that the one on the unregistration path
(which matters more) is removed by the next fix.

Fixes: ff927412

 ("net: introduce name_node struct to be used in hashlist")
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
1a83f4a7
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