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

Nikolay Aleksandrov nikolay at cumulusnetworks.com
Mon Apr 22 09:44:00 UTC 2019


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 at mellanox.com>
> Cc: Mike Manning <mmanning at vyatta.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 at cumulusnetworks.com>


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