Re: [PATCH 1/1] RDMA/rxe: Fix unsafe socket release during namespace cleanup

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2026/4/28 7:26, Leon Romanovsky 写道:
> On Mon, Apr 27, 2026 at 01:52:17PM -0700, yanjun.zhu wrote:
>> On 4/27/26 5:35 AM, Leon Romanovsky wrote:
>>> On Fri, Apr 24, 2026 at 06:35:22AM +0200, Zhu Yanjun wrote:
>>>> Since all the sockets are created in rdma link create command
>>>> and destroyed in rdma link delete command, keeping
>>>> udp_tunnel_sock_release in rxe_ns_exit risks a "double-free" if
>>>> the namespace and the device are being cleaned up simultaneously.
>>>
>>> Please add a ladder diagram to clarify how it can be possible.
>>
>> Hi, Leon
>>
>> The double-free occurs as follows:
>>
>> CPU 0 (Net NameSpace cleanup)        CPU 1 (RDMA device removal)
>> ---------------------                ---------------------------
>> rxe_ns_exit()                        rxe_link_delete() (rdma link del )
>>    -> sk = ns_sk->rxe_sk4               -> sk = ns_sk->rxe_sk4
>>    -> udp_tunnel_sock_release(sk)
>>       [Success: First Free]             -> udp_tunnel_sock_release(sk)
>>                                            [Crash: Double Free]
>>
>> After removing the socket release logic from rxe_ns_exit(), we ensure
>> that only the device destruction path (rxe_link_delete) is responsible
>> for freeing the tunnel sockets, effectively eliminating the double-free
>> problem.
> 
> I think it is possible to call rxe_ns_exit() without invoking
> rxe_link_delete(), and in that case the UDP socket will not be
> destroyed.

Thanks, my bad. I missed this scenario.

Zhu Yanjun

> 
> Thanks
> 
>>
>> I am not sure if I should put the above into the commit log.
>>
>> Thanks a lot.
>>
>> Zhu Yanjun
>>
>>>
>>> Thanks
>>>
>>>>
>>>> Fixes: 13f2a53c2a71 ("RDMA/rxe: Add net namespace support for IPv4/IPv6 sockets")
>>>> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
>>>> ---
>>>>    drivers/infiniband/sw/rxe/rxe_ns.c | 20 --------------------
>>>>    1 file changed, 20 deletions(-)
>>>>
>>>> diff --git a/drivers/infiniband/sw/rxe/rxe_ns.c b/drivers/infiniband/sw/rxe/rxe_ns.c
>>>> index 8b9d734229b2..53add78b8e3a 100644
>>>> --- a/drivers/infiniband/sw/rxe/rxe_ns.c
>>>> +++ b/drivers/infiniband/sw/rxe/rxe_ns.c
>>>> @@ -39,26 +39,6 @@ static void rxe_ns_exit(struct net *net)
>>>>    {
>>>>    	/* called when the network namespace is removed
>>>>    	 */
>>>> -	struct rxe_ns_sock *ns_sk = net_generic(net, rxe_pernet_id);
>>>> -	struct sock *sk;
>>>> -
>>>> -	rcu_read_lock();
>>>> -	sk = rcu_dereference(ns_sk->rxe_sk4);
>>>> -	rcu_read_unlock();
>>>> -	if (sk) {
>>>> -		rcu_assign_pointer(ns_sk->rxe_sk4, NULL);
>>>> -		udp_tunnel_sock_release(sk->sk_socket);
>>>> -	}
>>>> -
>>>> -#if IS_ENABLED(CONFIG_IPV6)
>>>> -	rcu_read_lock();
>>>> -	sk = rcu_dereference(ns_sk->rxe_sk6);
>>>> -	rcu_read_unlock();
>>>> -	if (sk) {
>>>> -		rcu_assign_pointer(ns_sk->rxe_sk6, NULL);
>>>> -		udp_tunnel_sock_release(sk->sk_socket);
>>>> -	}
>>>> -#endif
>>>>    }
>>>>    /*
>>>> -- 
>>>> 2.43.0
>>>>
>>>>
>>