Re: [Xen-ia64-devel] [PATCH] Fix vulnerability of copy_to_user in PAL emulation

[Tristan Gingold <tgingold@xxxxxxx>]

On Wed, Dec 12, 2007 at 06:15:34AM +0100, Tristan Gingold wrote:
> On Wed, Dec 12, 2007 at 01:07:13PM +0900, Kouya Shimura wrote:
> Content-Description: message body text
> > Hi Alex,
> > 
> > Thank you for reviewing. 
> > I updated the patch as your comments. please apply.
> > I also long for a xencomm.
> 
> For xencomm, I was maybe a little bit optimistic.  Xencomm requires a buffer
> in RAM, which is not esay (or possible) for static convention.  So we have
> to pass the content through registers...

My latest idea on this subject:

The buffers are small: 64 bytes.  So, instead of passing a buffer address,
return the buffer by register (using scratch register r14-r21).  The PAL
stub can then save it to memory.  I think this approach is the simplest
one.

Tristan.

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