From: Juergen Gross <jgross@suse.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
x86@kernel.org, linux-doc@vger.kernel.org
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
corbet@lwn.net, boris.ostrovsky@oracle.com
Subject: Re: PLEASE REVERT URGENTLY: Re: [PATCH v5 2/3] x86/boot: add acpi rsdp address to setup_header
Date: Sat, 10 Nov 2018 08:02:45 +0100 [thread overview]
Message-ID: <5a2f5cb8-7332-f490-eabf-cfcbdcd1abc4@suse.com> (raw)
In-Reply-To: <2934552c-d150-0afb-6fa9-9398cb94d86a@zytor.com>
On 10/11/2018 07:32, H. Peter Anvin wrote:
>>
>> Unfortunately there are many major distros shipping boot loaders which
>> write crap data past the end of setup_header.
>>
>
> Yes. We know that and it is resolved by:
>
> a) the length field in setup_header;
> b) the "sentinel" field which catches legacy non-compliant bootloaders.
Doesn't help for boot loaders reading struct setup_header from the
kernel image and then writing e.g. 512 bytes back to the setup_header
location. The sentinel is cleared and the length field just isn't
taken into account. And this is what happened.
>
>>>
>>> This field thus belongs in struct boot_params, not struct setup_header.
>>
>> Okay, I can change that. Hoping that all boot loaders really write
>> zeroes to that field in case they don't know it.
>>
>
> This is what we added the sentinel field for: bootloaders which don't zero
> unknown fields (read: Grub) will trigger the sentinel, and we wipe most of
> this structure.
Unfortunately the sentinel seems to be cleared by said broken grub.
Juergen
next prev parent reply other threads:[~2018-11-10 7:02 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 6:14 [PATCH v5 0/3] x86: make rsdp address accessible via boot params Juergen Gross
2018-10-10 6:14 ` [PATCH v5 1/3] x86/xen: fix boot loader version reported for pvh guests Juergen Gross
2018-10-10 6:14 ` [PATCH v5 2/3] x86/boot: add acpi rsdp address to setup_header Juergen Gross
2018-11-09 22:23 ` PLEASE REVERT URGENTLY: " H. Peter Anvin
2018-11-10 0:38 ` H. Peter Anvin
2018-11-10 6:26 ` Juergen Gross
2018-11-10 6:32 ` H. Peter Anvin
2018-11-10 7:02 ` Juergen Gross [this message]
2018-11-10 7:16 ` H. Peter Anvin
2018-11-10 9:03 ` Juergen Gross
2018-11-11 18:49 ` H. Peter Anvin
2018-11-19 16:48 ` Konrad Rzeszutek Wilk
2018-11-10 15:22 ` Juergen Gross
2018-11-11 23:58 ` hpa
2018-10-10 6:14 ` [PATCH v5 3/3] x86/acpi: take rsdp address for boot params if available Juergen Gross
2018-10-10 6:23 ` [PATCH v5 0/3] x86: make rsdp address accessible via boot params Ingo Molnar
2018-10-10 6:39 ` Juergen Gross
2018-10-10 7:19 ` Ingo Molnar
2018-10-10 7:28 ` Juergen Gross
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