netdev - Re: [bug report] devlink: Move devlink dev reload code to dev

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Message-ID: <35ekvmjyb4ty5vdkyspwirz4qoahotpow22zt4vkonqjmtqziz@yk6pwla34ayn>
Date: Wed, 19 Nov 2025 18:19:18 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Moshe Shemesh <moshe@...dia.com>, netdev@...r.kernel.org
Subject: Re: [bug report] devlink: Move devlink dev reload code to dev

Wed, Nov 19, 2025 at 09:55:58AM +0100, dan.carpenter@...aro.org wrote:
>Hello Moshe Shemesh,
>
>Commit c6ed7d6ef929 ("devlink: Move devlink dev reload code to dev")
>from Feb 2, 2023 (linux-next), leads to the following Smatch static
>checker warning:
>
>	net/devlink/dev.c:408 devlink_netns_get()
>	error: potential NULL/IS_ERR bug 'net'
>
>net/devlink/dev.c
>    378 static struct net *devlink_netns_get(struct sk_buff *skb,
>    379                                      struct genl_info *info)
>    380 {
>    381         struct nlattr *netns_pid_attr = info->attrs[DEVLINK_ATTR_NETNS_PID];
>    382         struct nlattr *netns_fd_attr = info->attrs[DEVLINK_ATTR_NETNS_FD];
>    383         struct nlattr *netns_id_attr = info->attrs[DEVLINK_ATTR_NETNS_ID];
>    384         struct net *net;
>    385 
>    386         if (!!netns_pid_attr + !!netns_fd_attr + !!netns_id_attr > 1) {
>    387                 NL_SET_ERR_MSG(info->extack, "multiple netns identifying attributes specified");
>    388                 return ERR_PTR(-EINVAL);
>    389         }
>    390 
>    391         if (netns_pid_attr) {
>    392                 net = get_net_ns_by_pid(nla_get_u32(netns_pid_attr));
>
>Smatch thinks that the "net = get_net(nsproxy->net_ns);" could mean that
>get_net_ns_by_pid() returns NULL.  I don't know if that's correct or not.
>If someone could tell me, then it's easy for me to add a line
>"get_net_ns_by_pid 0" to the smatch_data/db/kernel.delete.return_states
>file but I'd prefer to be sure before I do that...

I don't see how get_net() can return NULL.


>
>    393         } else if (netns_fd_attr) {
>    394                 net = get_net_ns_by_fd(nla_get_u32(netns_fd_attr));
>    395         } else if (netns_id_attr) {
>    396                 net = get_net_ns_by_id(sock_net(skb->sk),
>    397                                        nla_get_u32(netns_id_attr));
>    398                 if (!net)
>    399                         net = ERR_PTR(-EINVAL);
>    400         } else {
>    401                 WARN_ON(1);
>    402                 net = ERR_PTR(-EINVAL);
>    403         }
>    404         if (IS_ERR(net)) {
>    405                 NL_SET_ERR_MSG(info->extack, "Unknown network namespace");
>    406                 return ERR_PTR(-EINVAL);
>    407         }
>--> 408         if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) {
>    409                 put_net(net);
>    410                 return ERR_PTR(-EPERM);
>    411         }
>    412         return net;
>    413 }
>
>regards,
>dan carpenter
>