linux-kernel - Re: [PATCH] ARM: kernel: Detect DTB overwrite and error out

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Message-ID: <528E6553.9020608@wwwdotorg.org>
Date:	Thu, 21 Nov 2013 12:56:03 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	Joel Fernandes <joelf@...com>
CC:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	will.deacon@....com, rnayak@...com, santosh.shilimkar@...com,
	balbi@...com
Subject: Re: [PATCH] ARM: kernel: Detect DTB overwrite and error out

On 11/21/2013 12:48 PM, Joel Fernandes wrote:
> On 11/21/2013 10:48 AM, Stephen Warren wrote:
>> On 11/20/2013 09:04 PM, Joel Fernandes wrote:
>>> Kernel can silenty fail for DT-boot after the decompression stage, if DTB is
>>> overwritten. Instead of simply failing, we detect the condition and print an
>>> error.
>>>
>>> One may think that it is sufficient for the bootloader to place the DTB away
>>> from kernel, but this is not the right fix because: (1) We add more dependence
>>> to the bootloader's stupidity (2) the decompressed kernel end address is not
>>> known to the loader. Also, we shouldn't depend on bootloader for silently
>>> failing us, so we detect the condition and error out.
>>
>> If this problem happens, is there any guarantee that the kernel will
>> still execute far enough to actually print this error message? Can the
> 
> Yes, because till this point we don't depend on DTB yet. We're still just about
> to parse it. The problem detected here is the kernel overwriting the DTB, not
> the other way.

Ah yes, that makes sense. Thanks.
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