linux-kernel - Re: [PATCH 3.10 12/27] x86-64, espfix: Dont leak bits 31:16 of %esp returning to 16-bit stack

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Date:	Thu, 7 Aug 2014 10:13:55 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Luis Henriques <luis.henriques@...onical.com>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Brian Gerst <brgerst@...il.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Borislav Petkov <bp@...en8.de>,
	Andrew Lutomriski <amluto@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dirk Hohndel <dirk@...ndel.org>,
	Arjan van de Ven <arjan.van.de.ven@...el.com>,
	comex <comexk@...il.com>,
	Alexander van Heukelum <heukelum@...tmail.fm>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH 3.10 12/27] x86-64, espfix: Dont leak bits 31:16 of %esp
 returning to 16-bit stack

On Wed, Aug 06, 2014 at 08:24:17AM -0700, Greg Kroah-Hartman wrote:
> On Wed, Aug 06, 2014 at 04:16:20PM +0100, Luis Henriques wrote:
> > On Tue, Aug 05, 2014 at 11:14:04AM -0700, Greg Kroah-Hartman wrote:
> > <...>
> > > @@ -188,17 +193,21 @@ static void note_page(struct seq_file *m
> > >  		/*
> > >  		 * Now print the actual finished series
> > >  		 */
> > > -		seq_printf(m, "0x%0*lx-0x%0*lx   ",
> > > -			   width, st->start_address,
> > > -			   width, st->current_address);
> > > -
> > > -		delta = (st->current_address - st->start_address) >> 10;
> > > -		while (!(delta & 1023) && unit[1]) {
> > > -			delta >>= 10;
> > > -			unit++;
> > > +		if (!st->marker->max_lines ||
> > > +		    st->lines < st->marker->max_lines) {
> > > +			seq_printf(m, "0x%0*lx-0x%0*lx   ",
> > > +				   width, st->start_address,
> > > +				   width, st->current_address);
> > > +
> > > +			delta = (st->current_address - st->start_address) >> 10;
> > > +			while (!(delta & 1023) && unit[1]) {
> > > +				delta >>= 10;
> > > +				unit++;
> > > +			}
> > > +			seq_printf(m, "%9lu%c ", delta, *unit);
> > > +			printk_prot(m, st->current_prot, st->level);
> > >  		}
> > > -		seq_printf(m, "%9lu%c ", delta, *unit);
> > > -		printk_prot(m, st->current_prot, st->level);
> > > +		st->lines++;
> > >  
> > >  		/*
> > >  		 * We print markers for special areas of address space,
> > 
> > Hmm... the original commit has a 2nd hunk here that does seem to be
> > applicable to 3.10.  Was this dropped accidentally or on purpose?
> 
> I don't remember at all, sorry.  What is the hunk that I missed?

You are right, I somehow missed that, thanks.  I've also now fixed up
the ">> 10" change as well.  Good thing this is just in debugging code
:)

thanks,

greg k-h
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