netdev - Re: [PATCH net] net: fix possible store tearing in neigh_periodic

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Message-ID: <20230922094941.GZ224399@kernel.org>
Date: Fri, 22 Sep 2023 10:49:41 +0100
From: Simon Horman <horms@...nel.org>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net] net: fix possible store tearing in
 neigh_periodic_work()

On Thu, Sep 21, 2023 at 08:46:26AM +0000, Eric Dumazet wrote:
> While looking at a related syzbot report involving neigh_periodic_work(),
> I found that I forgot to add an annotation when deleting an
> RCU protected item from a list.
> 
> Readers use rcu_deference(*np), we need to use either
> rcu_assign_pointer() or WRITE_ONCE() on writer side
> to prevent store tearing.
> 
> I use rcu_assign_pointer() to have lockdep support,
> this was the choice made in neigh_flush_dev().
> 
> Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Reviewed-by: Simon Horman <horms@...nel.org>