6.1-stable review patch. If anyone has any objections, please let me know.
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From: Jakub Kicinski kuba@kernel.org
commit 1a83f4a7c156fa6bbd6b530e89fa3270bf3d9d1b upstream.
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: ff92741270bf ("net: introduce name_node struct to be used in hashlist") Reviewed-by: Jiri Pirko jiri@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/dev.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/core/dev.c +++ b/net/core/dev.c @@ -345,7 +345,6 @@ int netdev_name_node_alt_create(struct n static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node) { list_del(&name_node->list); - netdev_name_node_del(name_node); kfree(name_node->name); netdev_name_node_free(name_node); } @@ -364,6 +363,8 @@ int netdev_name_node_alt_destroy(struct if (name_node == dev->name_node || name_node->dev != dev) return -EINVAL;
+ netdev_name_node_del(name_node); + synchronize_rcu(); __netdev_name_node_alt_destroy(name_node);
return 0; @@ -10835,6 +10836,7 @@ void unregister_netdevice_many(struct li synchronize_net();
list_for_each_entry(dev, head, unreg_list) { + struct netdev_name_node *name_node; struct sk_buff *skb = NULL;
/* Shutdown queueing discipline. */ @@ -10860,6 +10862,9 @@ void unregister_netdevice_many(struct li dev_uc_flush(dev); dev_mc_flush(dev);
+ netdev_for_each_altname(dev, name_node) + netdev_name_node_del(name_node); + synchronize_rcu(); netdev_name_node_alt_flush(dev); netdev_name_node_free(dev->name_node);