netdev - Re: [PATCH net-next] bridge: Fix possible use-after-free when deleting bridge port

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Message-ID: <335b31d0-9a65-0a2d-2b6c-339e42eddad1@cumulusnetworks.com>
Date:   Mon, 22 Apr 2019 12:44:00 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Ido Schimmel <idosch@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bridge@...ts.linux-foundation.org" 
        <bridge@...ts.linux-foundation.org>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "roopa@...ulusnetworks.com" <roopa@...ulusnetworks.com>,
        mlxsw <mlxsw@...lanox.com>,
        Mike Manning <mmanning@...tta.att-mail.com>
Subject: Re: [PATCH net-next] bridge: Fix possible use-after-free when
 deleting bridge port

On 22/04/2019 12:33, Ido Schimmel wrote:
> When a bridge port is being deleted, do not dereference it later in
> br_vlan_port_event() as it can result in a use-after-free [1] if the RCU
> callback was executed before invoking the function.
> 
[snip]
> 
> Fixes: 9c0ec2e7182a ("bridge: support binding vlan dev link state to vlan member bridge ports")
> Signed-off-by: Ido Schimmel <idosch@...lanox.com>
> Cc: Mike Manning <mmanning@...tta.att-mail.com>
> ---
>  net/bridge/br.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br.c b/net/bridge/br.c
> index e69fc87a13e0..3c8e4b38f054 100644
> --- a/net/bridge/br.c
> +++ b/net/bridge/br.c
> @@ -129,7 +129,8 @@ static int br_device_event(struct notifier_block *unused, unsigned long event, v
>  		break;
>  	}
>  
> -	br_vlan_port_event(p, event);
> +	if (event != NETDEV_UNREGISTER)
> +		br_vlan_port_event(p, event);
>  
>  	/* Events that may cause spanning tree to refresh */
>  	if (!notified && (event == NETDEV_CHANGEADDR || event == NETDEV_UP ||
> 

Right, the br_del_if is just above. :)

Acked-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>