On 26 July 2017 at 15:22, Guillaume Nault <g.nault@xxxxxxxxxxxx> wrote:
> On Wed, Jul 26, 2017 at 02:15:15AM +0530, Amit Pundir wrote:
>> From: Guillaume Nault <g.nault@xxxxxxxxxxxx>
>>
>> commit 1f461dcdd296eecedaffffc6bae2bfa90bd7eb89 upstream.
>>
>> Let channels hold a reference on their network namespace.
>> Some channel types, like ppp_async and ppp_synctty, can have their
>> userspace controller running in a different namespace. Therefore they
>> can't rely on them to preclude their netns from being removed from
>> under them.
>>
> Hi Amit,
>
> I don't know how you got there, but one chunk is missing in your
> backport (same problem happened in your -4.4 series):
> @@ -2307,7 +2307,7 @@ int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
>
> pch->ppp = NULL;
> pch->chan = chan;
> - pch->chan_net = net;
> + pch->chan_net = get_net(net);
> chan->ppp = pch;
> init_ppp_file(&pch->file, CHANNEL);
> pch->file.hdrlen = chan->hdrlen;
>
> Also, any backport of commit 1f461dcdd296 ("ppp: take reference on channels netns")
> should be accompanied by commit 205e1e255c47 ("ppp: defer netns reference release for ppp channel").
>
> Anyway, both are already present in stable/linux-3.18.y, so this patch
> can be dropped from your series.
Thanks Guillaume. I realised that too earlier today. Somehow "git
cherry-pick" didn't complain this time. I replied on 4.4 series to
ignore this patch but forgot to do that on this 3.18 patch. Thanks for
pointing it out.
> And FWIW, I think linux-3.18.y isn't maintained anymore.
linux-3.18.y is still getting maintained. See
https://lkml.org/lkml/2017/4/16/209.
Regards,
Amit Pundir
>
>>
>> Fixes: 273ec51dd7ce ("net: ppp_generic - introduce net-namespace functionality v2")
>> Reported-by: Baozeng Ding <sploving1@xxxxxxxxx>
>> Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx>
>> Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
>> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
>> Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
>> ---
>> drivers/net/ppp/ppp_generic.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
>> index 3dd1c19756ec..38c0231fb9b7 100644
>> --- a/drivers/net/ppp/ppp_generic.c
>> +++ b/drivers/net/ppp/ppp_generic.c
>> @@ -2342,6 +2342,8 @@ ppp_unregister_channel(struct ppp_channel *chan)
>> spin_lock_bh(&pn->all_channels_lock);
>> list_del(&pch->list);
>> spin_unlock_bh(&pn->all_channels_lock);
>> + put_net(pch->chan_net);
>> + pch->chan_net = NULL;
>>
>> pch->file.dead = 1;
>> wake_up_interruptible(&pch->file.rwait);
>> --
>> 2.7.4
>>