On Tue, Jan 9, 2018 at 7:00 PM, Jason Wang <jasow...@redhat.com> wrote:
>
>
> On 2018年01月10日 08:07, Cong Wang wrote:
>>
>> tfile->tun could be detached before we close the tun fd,
>> via tun_detach_all(), so it should not be used to check for
>> tfile->tx_array.
>>
>> Use the same logic as in tun_attach(), just test !tfile->deatched.
>>
>> Reported-by: Dmitry Vyukov <dvyu...@google.com>
>> Fixes: 1576d9860599 ("tun: switch to use skb array for tx")
>> Cc: Jason Wang <jasow...@redhat.com>
>> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
>> ---
>> drivers/net/tun.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
>> index 4f4a842a1c9c..1a1f834440a6 100644
>> --- a/drivers/net/tun.c
>> +++ b/drivers/net/tun.c
>> @@ -613,6 +613,7 @@ static void tun_queue_purge(struct tun_file *tfile)
>> static void __tun_detach(struct tun_file *tfile, bool clean)
>> {
>> + bool clean_tx_array = !tfile->detached;
>> struct tun_file *ntfile;
>> struct tun_struct *tun;
>> @@ -657,7 +658,7 @@ static void __tun_detach(struct tun_file *tfile,
>> bool clean)
>> tun->dev->reg_state == NETREG_REGISTERED)
>> unregister_netdevice(tun->dev);
>> }
>> - if (tun)
>> + if (clean_tx_array)
>> skb_array_cleanup(&tfile->tx_array);
>> sock_put(&tfile->sk);
>> }
>
>
> Looks like we may still leak if we do
>
> open
> attach
> detach
> close
Good catch.
>
> Should we do cleanup unconditionally?
It doesn't look like we can, because tfile is not zero'ed at
least, it is allocated by sk_alloc() so tfile->tx_array could be
some random value which prevents skb_array_cleanup()
functioning correctly. Zero'ing tfile->tx_array in open()
is not sufficient, as spinlocks are not yet initialized.
I think we probably need to test tfile->tx_array.ring.queue,
it is ugly but I don't see there is an API for it.
