linux-kernel - Re: [PATCH 1/2] x86: Check return values from early

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Message-ID: <Y0GTUg1ACpKZYMHY@nazgul.tnic>
Date:   Sat, 8 Oct 2022 17:12:35 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ross Philipson <ross.philipson@...cle.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        dpsmith@...rtussolutions.com, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, luto@...capital.net, dave.hansen@...ux.intel.com,
        kanth.ghatraju@...cle.com, trenchboot-devel@...glegroups.com,
        Jan Kiszka <jan.kiszka@...mens.com>,
        jailhouse-dev@...glegroups.com, xen-devel@...ts.xenproject.org
Subject: Re: [PATCH 1/2] x86: Check return values from early_memremap calls

Adding Xen and Jailhouse people and MLs to Cc.

Folks, thread starts here:

https://lore.kernel.org/r/1650035401-22855-1-git-send-email-ross.philipson@oracle.com

On Fri, Apr 15, 2022 at 11:10:00AM -0400, Ross Philipson wrote:
> There are a number of places where early_memremap is called
> but the return pointer is not checked for NULL. The call
> can result in a NULL being returned so the checks must
> be added.
> 
> Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
> ---
>  arch/x86/kernel/devicetree.c | 10 ++++++++++
>  arch/x86/kernel/e820.c       |  5 +++++
>  arch/x86/kernel/jailhouse.c  |  6 ++++++
>  arch/x86/kernel/mpparse.c    | 23 +++++++++++++++++++++++
>  arch/x86/kernel/setup.c      |  5 +++++
>  arch/x86/xen/enlighten_hvm.c |  2 ++
>  arch/x86/xen/mmu_pv.c        |  8 ++++++++
>  arch/x86/xen/setup.c         |  2 ++
>  8 files changed, 61 insertions(+)

Ok, a couple of notes:

1. the pr_*("<prefix>:" ... )

thing is done using pr_fmt() - grep the tree for examples.

2. I think you should not panic() the machine but issue a the
warning/error and let the machine die a painful death anyway. But Xen
folks will know better what would be the optimal thing to do.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette