linux-kernel - Re: [PATCH v2 1/3] ima: Add ima_validate_range() for previous kernel IMA buffer

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Message-ID: <29879a797996a14547c1274c45a4e7b824ab95d3.camel@linux.ibm.com>
Date: Tue, 30 Dec 2025 15:35:50 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
Cc: akpm@...ux-foundation.org, ardb@...nel.org, bp@...en8.de,
        dave.hansen@...ux.intel.com, graf@...zon.com,
        guoweikang.kernel@...il.com, henry.willard@...cle.com, hpa@...or.com,
        jbohac@...e.cz, joel.granados@...nel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, noodles@...com, paul.x.webb@...cle.com,
        rppt@...nel.org, sohil.mehta@...el.com, sourabhjain@...ux.ibm.com,
        stable@...r.kernel.org, tglx@...utronix.de, x86@...nel.org,
        yifei.l.liu@...cle.com
Subject: Re: [PATCH v2 1/3] ima: Add ima_validate_range() for previous
 kernel IMA buffer

Hi Harshit,

The subject line could be written at a higher level.  Perhaps base it on the
ima_validate_range() function comment "verify a physical buffer lies in
addressable RAM" (e.g. ima: verify the previous kernel's IMA buffer lies in
addressable RAM). 

On Mon, 2025-12-29 at 00:15 -0800, Harshit Mogalapalli wrote:
> When the second-stage kernel is booted with a limiting command line
> (e.g. "mem=<size>"), the IMA measurement buffer handed over from the
> previous kernel may fall outside the addressable RAM of the new kernel.
> Accessing such a buffer can fault during early restore.
> 
> Introduce a small generic helper, ima_validate_range(), which verifies
> that a physical [start, end] range for the previous-kernel IMA buffer
> lies within addressable memory:
> 	- On x86, use pfn_range_is_mapped().
> 	- On OF based architectures, use page_is_ram().
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>

-- 
thanks,

Mimi