Re: Sed-opal fixups

[Scott Bauer]

On Thu, Feb 09, 2017 at 05:43:20PM +0000, David Laight wrote:
> From: Scott Bauer
> > Sent: 09 February 2017 17:20
> > It may be too late to change anyhting in the uapi header. When we
> > switched over to using IOC_SIZE I found a bug where I had switched
> > up a structure in one of the series from v4 to v5 but never changed
> > the structure in the IOW. The structure that was in there was to small
> > so when we kzalloc on it we don't request enough space. It worked before
> > because we were using the cmd strictly as a command #, not using the IOC
> > and friends.
> > 
> > If it's too late to modify that IOW, I can work around it by reallocing
> > on the correct size for that command only. I verified the rest of the
> > commands and the structures are the same.
> > 
> > Let me know what you think, please.
> 
> Maybe define IOC_OPAL_ACTIVATE_LSP_OLD to the incorrect value and
> IOC_OPAL_ACTIVATE_LSP to the correct one.
> But that relies on any users specifying the correct structure.
> I wouldn't guarantee that.

I think I'm the only userspace user right now, this went in on monday,
so I can can change my tooling easily. I just wasnt sure if there was a
set time where the user ABI cannot be changed.

> 
> At the top of the driver's ioctl path add:
> 	if (cmd == IOC_OPAL_ACTIVATE_LSP_OLD) cmd = IOC_OPAL_ACTIVATE_LSP;
>

I think it would have to be the other way around the correct sized one would
be IOC_OPAL_ACTIAVE_LSP_NEW so the check would be:
if (cmd == IOC_OPAL_ACTIVATE_LSP) cmd = IOC_OPAL_ACTIVATE_LSP_NEW. If we're
allowed to change it (the bad sized one) from LSP to LSP_OLD then we should
just change the structure. If we have to leave it we need to introduce a _NEW
with the correct size.


> For some code I added a userspace wrapper on ioctl() to check the
> size of the supplied arg matched that required by the 'cmd'.
> I've also done the same in the kernel.
> (all as compile time checks).
> 
> 	David
> 
>