Re: [PATCH] x86/kexec: Add a sanity check on previous kernel's ima kexec buffer

[Mimi Zohar <zohar@linux.ibm.com>]

On Mon, 2025-12-01 at 15:03 +0530, Harshit Mogalapalli wrote:
> Hi all,
> 
> On 13/11/25 01:00, Harshit Mogalapalli wrote:
> > When the second-stage kernel is booted via kexec with a limiting command
> > line such as "mem=<size>", the physical range that contains the carried
> > over IMA measurement list may fall outside the truncated RAM leading to
> > a kernel panic.
> > 
> >      BUG: unable to handle page fault for address: ffff97793ff47000
> >      RIP: ima_restore_measurement_list+0xdc/0x45a
> >      #PF: error_code(0x0000) – not-present page
> > 
> > Other architectures already validate the range with page_is_ram(), as
> > done in commit: cbf9c4b9617b ("of: check previous kernel's
> > ima-kexec-buffer against memory bounds") do a similar check on x86.

It should be obvious that without carrying the measurement list across kexec,
that attestation will fail.  Please mentioned it here in the patch description.

> > 
> > Cc: stable@vger.kernel.org
> > Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
> > Reported-by: Paul Webb <paul.x.webb@oracle.com>
> > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>

Tested-by: Mimi Zohar <zohar@linux.ibm.com>
>