From: Juergen Gross <jgross@suse.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
x86@kernel.org, lenb@kernel.org, rafael.j.wysocki@intel.com,
hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com
Subject: Re: [PATCH] x86/acpi: check rsdp address received via bootparams to be valid
Date: Tue, 16 Jan 2018 16:56:21 +0100 [thread overview]
Message-ID: <432c21ab-24d8-1e70-a471-ad8a14357d4e@suse.com> (raw)
In-Reply-To: <20180116154630.ke53suvokynj73qd@gmail.com>
On 16/01/18 16:46, Ingo Molnar wrote:
>
> * Juergen Gross <jgross@suse.com> wrote:
>
>> There seem to exist several grub2 versions trashing
>> boot_params.hdr.acpi_rsdp_addr.
>>
>> So don't just believe this address to be valid, but verify it pointing
>> to a valid RSDP table.
>
> Exactly what kind of values do those Grub2 versions put into that field? Pointer
> to something, or random noise?
Looks like random noise. On Mike's system it was 0x000000000151.
> Also, what exactly does 'validation' mean, how robustly does it filter out of spec
> uses of the boot protocol?
It validates the RSDP has the correct 8 byte eye catcher in it and
the checksum of the structure is correct. Searching the RSDP by
scanning memory is using the same checks, so I guess this ought to
be okay. Odds are about 1 : 2^80 for false positives.
Juergen
next prev parent reply other threads:[~2018-01-16 15:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-16 13:57 [PATCH] x86/acpi: check rsdp address received via bootparams to be valid Juergen Gross
2018-01-16 15:46 ` Ingo Molnar
2018-01-16 15:56 ` Juergen Gross [this message]
2018-01-16 16:35 ` Ingo Molnar
2018-01-17 12:28 ` Juergen Gross
2018-01-17 15:34 ` Ingo Molnar
2018-01-17 18:12 ` Juergen Gross
2018-02-13 16:32 ` Ingo Molnar
2018-02-13 16:48 ` Juergen Gross
2018-01-17 11:49 ` Rafael J. Wysocki
2018-01-17 12:20 ` Juergen Gross
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