Re: [RFC][PATCH] Randomize kernel base address on boot

Vivek Goyal
2011-05-26T20:32:26Z

On Thu, May 26, 2011 at 04:16:05PM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Thu, 26 May 2011 16:01:21 EDT, Vivek Goyal said:
>
> > Also randomization of kernel load address at run time will probably have
> > some issues with crashkernel=X@Y address syntax. So far user knew what
> > address first kernel is booting from and user could speicy where to
> > reserve memory. Now it might happen that user specified some memory
> > to reserve and kernel decided to occupy that space resulting in failed
> > memory reservation for crash kernel.
>
> That is however fixable - the randomizer just needs to make sure it doesn't
> overlay the crashkernel= space, and the crashkernel needs to be started with a
> 'norandomize' parameter.

That can be done but at the same time if kernel does not find any suitable
range to boot from, it should override crashkernel=X@Y settings and fail
crash memory reservation.

I guess with randomize space thing a more suitable crash kernel command
line will be crashkernel=X where kernel decides the base address for
second kernel depending on availability.

> If your threat model includes attacks on the
> crashkernel that randomizing will help with, you got bigger problems. ;)
>

:-) I think norandomize for kdump kernel should be just fine.

Thanks
Vivek