Re: ptrval hiding -- first kernel messages look rather "interesting"
From: Pavel Machek
Date: Fri Jun 01 2018 - 06:57:33 EST
On Fri 2018-06-01 13:49:41, Andy Shevchenko wrote:
> On Fri, Jun 1, 2018 at 1:31 PM, Pavel Machek <pavel@xxxxxx> wrote:
> > Hi!
> >
> > v4.17 on n900:
> >
> > [ 0.000000] Virtual kernel memory layout:
> > [ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
> > [ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
> > [ 0.000000] vmalloc : 0xd0000000 - 0xff800000 ( 760 MB)
> > [ 0.000000] lowmem : 0xc0000000 - 0xcff00000 ( 255 MB)
> > [ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
> > [ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
> > [ 0.000000] .text : 0x(ptrval) - 0x(ptrval) (8160 kB)
> > [ 0.000000] .init : 0x(ptrval) - 0x(ptrval) (1024 kB)
> > [ 0.000000] .data : 0x(ptrval) - 0x(ptrval) ( 309 kB)
> > [ 0.000000] .bss : 0x(ptrval) - 0x(ptrval) ( 333 kB)
> > [ 0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
> >
> > I mean -- security is nice, but perhaps we should adjust the messages
> > so this does not look like we are making fun of the user?
>
> Colleague of mine (perhaps you even know him) wrote recently a small
> patch that improves kernel by 400% by removing ptr_to_id() completely.
>
> Okay, joking is joking, but it was a proposal to have some command
> line option to enforce no-hash pointers.
> I would rather enable it when one of the existing option is present
> (like 'debug'), though it might alter the output in user space or
> something else.
> So, I have no strong opinion here.
I guess my proposal would be replacing the four lines with single line:
.text (8160 kB) .init (1024 kB) .data ( 309 kB) .bss ( 333 kB)
I'm not sure if exact addresses are normally useful, and having big
table saying "redacted!" looks strange.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
Attachment:
signature.asc
Description: Digital signature