netdev - Re: [PATCH net v3] ipv6: add rcu grace period before freeing fib6

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Message-Id: <20170822.110334.1274898045765726227.davem@davemloft.net>
Date:   Tue, 22 Aug 2017 11:03:34 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     weiwan@...gle.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, kafai@...com
Subject: Re: [PATCH net v3] ipv6: add rcu grace period before freeing
 fib6_node

From: Wei Wang <weiwan@...gle.com>
Date: Mon, 21 Aug 2017 09:47:10 -0700

> From: Wei Wang <weiwan@...gle.com>
> 
> We currently keep rt->rt6i_node pointing to the fib6_node for the route.
> And some functions make use of this pointer to dereference the fib6_node
> from rt structure, e.g. rt6_check(). However, as there is neither
> refcount nor rcu taken when dereferencing rt->rt6i_node, it could
> potentially cause crashes as rt->rt6i_node could be set to NULL by other
> CPUs when doing a route deletion.
> This patch introduces an rcu grace period before freeing fib6_node and
> makes sure the functions that dereference it takes rcu_read_lock().
> 
> Note: there is no "Fixes" tag because this bug was there in a very
> early stage.
> 
> Signed-off-by: Wei Wang <weiwan@...gle.com>
> Acked-by: Eric Dumazet <edumazet@...gle.com>
> Acked-by: Martin KaFai Lau <kafai@...com>

Applied and queued up for -stable, thanks.