Re: [PATCH] dma-direct: use the correct size for dma_set_encrypted()

[Robin Murphy]

On 2022-06-23 08:00, Dexuan Cui wrote:
> > From: Christoph Hellwig <hch@xxxxxx>
> > Sent: Wednesday, June 22, 2022 10:44 PM
> > To: Dexuan Cui <decui@xxxxxxxxxxxxx>
> >   ...
> > On Wed, Jun 22, 2022 at 12:14:24PM -0700, Dexuan Cui wrote:
> > > The third parameter of dma_set_encrypted() is a size in bytes rather than
> > > the number of pages.
> > >
> > > Fixes: 4d0564785bb0 ("dma-direct: factor out dma_set_{de,en}crypted
> > helpers")
> > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> >
> > see:
> >
> > commit 4a37f3dd9a83186cb88d44808ab35b78375082c9 (tag:
> > dma-mapping-5.19-2022-05-25)
> > Author: Robin Murphy <robin.murphy@xxxxxxx>
> > Date:   Fri May 20 18:10:13 2022 +0100
> >
> >      dma-direct: don't over-decrypt memory
>
> It looks like commit 4a37f3dd9a831 fixed a different issue?
>
> Here my patch is for the latest mainline:
>
> In dma_direct_alloc()'s error handling path, we pass 'size' to dma_set_encrypted():
>    out_encrypt_pages:
> 	  if (dma_set_encrypted(dev, page_address(page), size))
>
> However, in dma_direct_free(), we pass ' 1 << page_order ' to dma_set_encrypted().
> I think the ' 1 << page_order' is incorrect and it should be 'size' as well?

I think technically you're both right - these instances clearly have a 
history tracing back to the original bug that my patch addressed, but 
the refactoring then made them into their own distinct bug in terms of 
the internal dma_set_encrypted() interface, per the commit message here. 
Apparently I failed to spot this when forward-porting 4a37f3dd9a831 from 
5.10 (as the commit message says, don't ask... ;) ) - I guess I was only 
looking at where the set_memory_*() callsites had moved to. For this patch,

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>

Thanks
Robin.