linux-kernel - Re: [PATCH 0/5] tun/macvtap: TUNSETIFF fixes

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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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