Re: [PATCH v4 1/7] kexec_file: allow to place kexec_buf randomly

[Coiby Xu]

On Tue, Jun 04, 2024 at 03:41:35PM +0800, Baoquan He wrote:
> On 05/23/24 at 01:04pm, Coiby Xu wrote:
> > Currently, kexec_buf is placed in order which means for the same
> > machine, the info in the kexec_buf is always located at the same
> > position each time the machine is booted. This may cause a risk for
> > sensitive information like LUKS volume key. Now struct kexec_buf has a
> > new field random which indicates it's supposed to be placed in a random
> > position.
> >
> > Suggested-by: Jan Pazdziora <jpazdziora@xxxxxxxxxx>
> > Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
> > ---
> >  include/linux/kexec.h |  2 ++
> >  kernel/kexec_file.c   | 15 +++++++++++++++
> >  2 files changed, 17 insertions(+)
> >
> > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> > index f0e9f8eda7a3..cc81b8a903ab 100644
> > --- a/include/linux/kexec.h
> > +++ b/include/linux/kexec.h
[...]
> > @@ -445,6 +456,8 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
> >
> >  	temp_end = min(end, kbuf->buf_max);
> >  	temp_start = temp_end - kbuf->memsz + 1;
> > +	if (kbuf->random)
> > +		temp_start = kexec_random_start(temp_start, temp_end);
>
> As we discussed before, this need be limited in kdump scope, seems v4
> doesn't include the change.

Yes, v4 was sent mainly for you to review the patches by applying to
latest Linus tree. v5 now include the change.

--
Best regards,
Coiby