linux-kernel - Re: [PATCH v2 3/3] x86/kexec: Add a sanity check on previous kernel's ima kexec buffer

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Message-ID: <a5fbf391731b04b5cea5aa2202f375986ea90991.camel@linux.ibm.com>
Date: Tue, 30 Dec 2025 18:45:02 -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 3/3] x86/kexec: Add a sanity check on previous
 kernel's ima kexec buffer

On Mon, 2025-12-29 at 00:15 -0800, 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.
> 
> Without carrying the measurement list across kexec, the attestation
> would fail.
> 
> Cc: stable@...r.kernel.org
> Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
> Reported-by: Paul Webb <paul.x.webb@...cle.com>
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
> ---
> V1-> V2: Added a line about carrying measure list across kexec based on
> suggestion from Mimi Zohar. Made use to the new generic helper
> [Suggestion from Borislav]

Thanks, Harshit.

Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>