Re: [PATCH] IB/mlx5: add checking for "vf" from do_setvfinfo()

[Dan Carpenter <dan.carpenter@oracle.com>]

On Mon, Apr 22, 2019 at 03:09:00PM +0000, Parav Pandit wrote:
> Hi Dan,
> 
> > -----Original Message-----
> > From: Dan Carpenter <dan.carpenter@oracle.com>
> > Sent: Monday, April 22, 2019 3:09 AM
> > To: Parav Pandit <parav@mellanox.com>
> > Cc: Leon Romanovsky <leon@kernel.org>; Eli Cohen <eli@mellanox.com>;
> > Doug Ledford <dledford@redhat.com>; Jason Gunthorpe <jgg@ziepe.ca>;
> > linux-rdma@vger.kernel.org; kernel-janitors@vger.kernel.org
> > Subject: Re: [PATCH] IB/mlx5: add checking for "vf" from do_setvfinfo()
> > 
> > On Tue, Apr 16, 2019 at 10:54:42PM +0000, Parav Pandit wrote:
> > > > Yeah.  But the call tree here is:
> > > >
> > > > do_setvfinfo()
> > > > -> ops->ndo_get_vf_config()
> > > >    -> rtnl_fill_vfinfo()
> > > >       -> dev->netdev_ops->ndo_get_vf_config(dev, vfs_num, &ivi)
> > > >          -> ipoib_get_vf_config()
> > > >             -> ib_get_vf_config
> > > >                -> device->ops.get_vf_config(device, vf, port, info);
> > > >
> > > > Changing the ->ndo_get_vf_config() pointer means you have to update
> > > > 20 functions in various drivers.  It becomes quite involved.  We
> > > > should apply this simple self contained fix then worry about doing other
> > cleanups later.
> > > >
> > > But if a static checker is run on following functions, they need for vf < 0
> > check.
> > >
> > > i40e_ndo_get_vf_config
> > > mlx5e_get_vf_config
> > > bnxt_get_vf_config
> > > etc and few more.
> > 
> > I checked again to see if it was "20 functions" or if it was "etc and few
> > more"...  It turns out its only 18 functions because I double counted two
> > functions at first.  Here is the list:
> > 
> > be_get_vf_config
> > bnx2x_get_vf_config
> > bnxt_get_vf_config
> > cxgb4_mgmt_get_vf_config
> > efx_sriov_get_vf_config
> > fm10k_ndo_get_vf_config
> > i40e_ndo_get_vf_config
> > ice_get_vf_cfg
> > igb_ndo_get_vf_config
> > ipoib_get_vf_config
> > ixgbe_ndo_get_vf_config
> > liquidio_get_vf_config
> > mlx4_en_get_vf_config
> > mlx5e_get_vf_config
> > nfp_app_get_vf_config
> > nsim_get_vf_config
> > qede_get_vf_config
> > qlcnic_sriov_get_vf_config
> > 
> > But you also have to update the call tress as well...  It's really very involved.  I
> > seriously did look at how to do this and the original patch is the Right Thing
> > To Do [tm].  I've probably sent around 92 underflow patches and sometimes
> > I would definitely agree with you that changing the type is the right fix but
> > not in this case.
> > 
> Do you plan to fix all the above functions for < 0?
> There are other several other ndo_get_vf_* functions who need < 0 check. What about them?
> Will you fix them as well?

Oh wow...  I'm looking at these now and there are a lot of bugs.  You
are right.  To be honest, though, I'm tempted to just add a check for
negatives in the core...  I know you don't like that...

My static analysis was supposed to catch these underflows.  It's the end
of the day for me, but I will get this working tomorrow.

> Instead of doing all those fixes, why not use right u32 data type to eliminate < 0 check?
> 
> What about sriov getting disabled right after > vf check passes?

I don't know the subsystem well enough to answer this question.  What
do you suggest?

regards,
dan carpenter