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Message-ID: <20231017075259.5876c644@kernel.org> Date: Tue, 17 Oct 2023 07:52:59 -0700 From: Jakub Kicinski <kuba@...nel.org> To: Jiri Pirko <jiri@...nulli.us> Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com Subject: Re: [PATCH net 3/5] net: avoid UAF on deleted altname On Tue, 17 Oct 2023 09:51:02 +0200 Jiri Pirko wrote: > >but freed by kfree() with no synchronization point. > > > >Because the name nodes don't hold a reference on the netdevice > >either, take the heavier approach of inserting synchronization > > What about to use kfree_rcu() in netdev_name_node_free() > and treat node_name->dev as a rcu pointer instead? > > struct net_device *dev_get_by_name_rcu(struct net *net, const char *name) > { > struct netdev_name_node *node_name; > > node_name = netdev_name_node_lookup_rcu(net, name); > return node_name ? rcu_deferecence(node_name->dev) : NULL; > } > > This would avoid synchronize_rcu() in netdev_name_node_alt_destroy() > > Btw, the next patch is smooth with this. As I said in the commit message, I prefer the explicit sync. Re-inserting the device and taking refs already necessitate it.
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