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Message-Id: <1418785912.6058.0@smtp.corp.redhat.com>
Date: Wed, 17 Dec 2014 03:19:52 +0008
From: Jason Wang <jasowang@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: linux-kernel@...r.kernel.org, David Miller <davem@...emloft.net>,
netdev@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH 0/5] tun/macvtap: TUNSETIFF fixes
On Tue, Dec 16, 2014 at 9:04 PM, Michael S. Tsirkin <mst@...hat.com>
wrote:
> Dan Carpenter reported the following:
> static checker warning:
>
> drivers/net/tun.c:1694 tun_set_iff()
> warn: 0x17100 is larger than 16 bits
>
> drivers/net/tun.c
> 1692
> 1693 tun->flags = (tun->flags & ~TUN_FEATURES) |
> 1694 (ifr->ifr_flags & TUN_FEATURES);
> 1695
>
> It's complaining because the "ifr->ifr_flags" variable is a short
> (should it be unsigned?). The new define:
>
> #define IFF_VNET_LE 0x10000
>
> doesn't fit in two bytes. Other suspect looking code could be:
>
> return __virtio16_to_cpu(q->flags & IFF_VNET_LE, val);
>
> And that's true: we have run out of IFF flags in tun.
I don't have objections on this series.
Just note that we still have several bits available.
>
> So let's not try to add more: add simple GET/SET ioctls
> instead. Easy to test, leads to clear semantics.
>
> Alternatively we'll have to revert the whole thing for 3.19,
> but that seems more work as this has dependencies
> in other places.
>
> While here, I noticed that macvtap was actually reading
> ifreq flags as a 32 bit field.
> Fix that up as well.
>
> Michael S. Tsirkin (5):
> macvtap: fix uninitialized access on TUNSETIFF
> if_tun: add TUNSETVNETLE/TUNGETVNETLE
> tun: drop broken IFF_VNET_LE
> macvtap: drop broken IFF_VNET_LE
> if_tun: drop broken IFF_VNET_LE
>
> include/uapi/linux/if_tun.h | 3 ++-
> drivers/net/macvtap.c | 30 ++++++++++++++++++++++++------
> drivers/net/tun.c | 26 +++++++++++++++++++++++---
> 3 files changed, 49 insertions(+), 10 deletions(-)
>
> --
> MST
>
> --
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