linux-kernel - Re: [PATCH] ACPI/PPTT: fix off-by-one error

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Message-ID: <20250506-shapeless-merciful-inchworm-7bfdb4@sudeepholla>
Date: Tue, 6 May 2025 14:43:39 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: "Heyne, Maximilian" <mheyne@...zon.de>
Cc: "stable@...r.kernel.org" <stable@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, Ard Biesheuvel <ardb@...nel.org>,
	Sudeep Holla <sudeep.holla@....com>,
	Jeremy Linton <jeremy.linton@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI/PPTT: fix off-by-one error

On Tue, May 06, 2025 at 01:13:02PM +0000, Heyne, Maximilian wrote:
> Commit 7ab4f0e37a0f ("ACPI PPTT: Fix coding mistakes in a couple of
> sizeof() calls") corrects the processer entry size but unmasked a longer
> standing bug where the last entry in the structure can get skipped due
> to an off-by-one mistake if the last entry ends exactly at the end of
> the ACPI subtable.
>

Unless the firmware has populated an incorrect value for the header length, I
don't see how this is possible. The table_end should point to the address
immediately following the last byte of the table. None of the headers are only
one byte long, so what am I missing that could explain this apparent
off-by-one issue?.

-- 
Regards,
Sudeep