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

["yanjun.zhu" <yanjun.zhu@linux.dev>]

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 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
>>
>>