netdev - Re: [net-next][PATCH] net/ipv4: fix a net leak

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Message-ID: <6b3baf53-3004-abac-ab49-9b2454858686@gmail.com>
Date:   Thu, 25 Oct 2018 12:46:14 -0600
From:   David Ahern <dsahern@...il.com>
To:     Bjørn Mork <bjorn@...k.no>
Cc:     Li RongQing <lirongqing@...du.com>, netdev@...r.kernel.org,
        David Miller <davem@...emloft.net>
Subject: Re: [net-next][PATCH] net/ipv4: fix a net leak

On 10/25/18 12:43 PM, Bjørn Mork wrote:
> 
> inet_valid_dump_ifaddr_req() will bail out with an error, but only
> *after* setting fillargs->netnsid:
> 
>                 if (i == IFA_TARGET_NETNSID) {
>                         struct net *net;
> 
>                         fillargs->netnsid = nla_get_s32(tb[i]);
> 
>                         net = rtnl_get_net_ns_capable(sk, fillargs->netnsid);
>                         if (IS_ERR(net)) {
>                                 NL_SET_ERR_MSG(extack, "ipv4: Invalid target network namespace id");
>                                 return PTR_ERR(net);
>                         }
>                         *tgt_net = net;
>                 } else {
> 
> 
> 
> So inet_dump_ifaddr() ends up doing put_net(tgt_net):
> 
> 
>                 err = inet_valid_dump_ifaddr_req(nlh, &fillargs, &tgt_net,
>                                                  skb->sk, cb);
>                 if (err < 0)
>                         goto put_tgt_net;
> ..
> put_tgt_net:
>         if (fillargs.netnsid >= 0)
>                 put_net(tgt_net);
> 
> 
> 
> I believe you should set fillargs->netnsid back to -1 in the
> inet_valid_dump_ifaddr_req() error path, or use a temp variable to avoid
> changing it unless get_net is successful.

good point. either use of an intermediate or resetting nsid on failure.
Will you send a patch to fix ipv4 and v6?

Thanks,