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Date: Wed, 10 Jan 2018 20:10:44 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Jean Delvare <jdelvare@suse.de>
Cc: stable@vger.kernel.org, Ales Novak <alnovak@suse.cz>,
        Seunghun Han <kkamagui@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Vikas C Sajjan <vikas.cha.sajjan@hpe.com>,
        Sunil V L <sunil.vl@hpe.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: Regression caused by commit dad5ab0db8de ("x86/acpi: Prevent out
 of bound access caused by broken ACPI tables")
Message-ID: <20180110191044.GA15591@kroah.com>
References: <20180110192822.1cf7d84c@endymion>
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On Wed, Jan 10, 2018 at 07:28:22PM +0100, Jean Delvare wrote:
> Hi all,
> 
> Commit dad5ab0db8de ("x86/acpi: Prevent out of bound access caused by
> broken ACPI tables") was tagged for stable and merged in various stable
> kernel trees (at least 3.2, 3.16, 3.18, 4.1, 4.4, 4.9 and 4.12.)
> 
> However it turns out that this commit introduced a regression on some
> systems (in particular HPE Superdome 2, but possibly others.) The fix
> for this breakage is:
> 
> commit 252714155f04c5d16989cb3aadb85fd1b5772f99
> Author: Vikas C Sajjan
> Date:   Thu Nov 16 21:43:44 2017 +0530
> 
>     x86/acpi: Handle SCI interrupts above legacy space gracefully
> 
> (and follow-up cleanup 4ee2ec1b1225 "x86/acpi: Reduce code duplication
> in mp_override_legacy_irq()".) Unfortunately the fix-up patch was NOT
> tagged for stable and also lacks a Fixes tag referring to the faulty
> commit. As a consequence nobody realized they fix a regression, and this
> regression is still present in all the aforementioned stable branches.
> 
> So I invite the maintainers of these stable kernel branches to backport
> commits 252714155f04 and possibly 4ee2ec1b1225 to solve this issue.

Many thanks for the report, I've queued up 252714155f04 now.  I don't
think 4ee2ec1b1225 needs to be merged, unless the acpi maintainers think
it is a good idea to do so.

Rafael, any thoughts?

thanks,

greg k-h