linux-kernel - Re: [PATCH] ACPICA: Tables: Skip NULL entries in RSDT and XSDT.

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Date:	Thu, 17 Apr 2014 19:44:26 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Lv Zheng <lv.zheng@...el.com>
Cc:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Len Brown <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	linux-acpi@...r.kernel.org, Zhao Yakui <yakui.zhao@...el.com>
Subject: Re: [PATCH] ACPICA: Tables: Skip NULL entries in RSDT and XSDT.

On Fri, Apr 18, 2014 at 09:53:19AM +0800, Lv Zheng wrote:
> Note that this patch is only used for stable kernels, upstream kernels
> will have this problem fixed in ACPICA 201303-04 release.  So upstream
> kernels shouldn't merge this commit.

What kernel commit fixed this issue in "upstream"?

> It is reported that there are buggy BIOSes in the world: AMI uses a XSDt
> compiler for early BIOSes, this compiler will generate XSDT with a NULL
> entry.  The affected BIOS versions are "AMI BIOS F2-F4".
> 
> Original solution on Linux is to use an alternative heathy root table
> instead of the ill one.  This commit is refined by the following ACPICA
> commit that tries to reduce the source code differences between Linux and
> ACPICA upstream.
>   Commit: 671cc68dc61f029d44b43a681356078e02d8dab8
>   Subject: ACPICA: Back port and refine validation of the XSDT root table.
> But according to the bug report, the XSDT in fact is not broken, we should
> just add NULL entry sanity check before installing a table address from
> XSDT.
> 
> With the NULL entry sanity check implemented, the XSDT validation is
> useless because:
> 1. If XSDT contains NULL entries, it can be bypassed by the new sanity
>    check mechanism;
> 2. If RSDP contains a bad XSDT address, invoking XSDT validation will still
>    lead to kernel crash.
> 
> This patch deletes XSDT validation logics and adds code to skip NULL
> entries that can be found in RSDT or XSDT. Lv Zheng.
> 
> Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=73911
> Buglink: https://bugs.archlinux.org/task/39811
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> Reported-and-tested-by: Bruce Chiarelli <mano155@...il.com>
> Reported-and-tested-by: Spyros Stathopoulos <spystath@...il.com>
> Cc: Zhao Yakui <yakui.zhao@...el.com>
> Cc: <stable@...r.kernel.org> # 3.14.x: 671cc68: ACPICA: Back port and refine validation of the XSDT root table.

So this fix is only needed for 3.14?  Or older?  I'm confused here...

greg k-h
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