netdev - Re: [PATCHv2 net 1/3] sctp: hold transport instead of assoc in sctp

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Message-ID: <20161031201418.GC8514@localhost.localdomain>
Date:   Mon, 31 Oct 2016 18:14:18 -0200
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        davem@...emloft.net, Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>
Subject: Re: [PATCHv2 net 1/3] sctp: hold transport instead of assoc in
 sctp_diag

On Mon, Oct 31, 2016 at 08:32:31PM +0800, Xin Long wrote:
> In sctp_transport_lookup_process(), Commit 1cceda784980 ("sctp: fix
> the issue sctp_diag uses lock_sock in rcu_read_lock") moved cb() out
> of rcu lock, but it put transport and hold assoc instead, and ignore
> that cb() still uses transport. It may cause a use-after-free issue.
> 
> This patch is to hold transport instead of assoc there.
> 
> Fixes: 1cceda784980 ("sctp: fix the issue sctp_diag uses lock_sock in rcu_read_lock")
> Signed-off-by: Xin Long <lucien.xin@...il.com>

Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>

> ---
>  net/sctp/socket.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 9fbb6fe..71b75f9 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -4480,12 +4480,9 @@ int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *),
>  	if (!transport || !sctp_transport_hold(transport))
>  		goto out;
>  
> -	sctp_association_hold(transport->asoc);
> -	sctp_transport_put(transport);
> -
>  	rcu_read_unlock();
>  	err = cb(transport, p);
> -	sctp_association_put(transport->asoc);
> +	sctp_transport_put(transport);
>  
>  out:
>  	return err;
> -- 
> 2.1.0
> 
> --
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