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Re: [Xen-devel] /dev/mem

from [Jan Beulich]

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To:	"Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject:	Re: [Xen-devel] /dev/mem
From:	"Jan Beulich" <JBeulich@xxxxxxxxxx>
Date:	Wed, 25 Jan 2006 09:24:07 +0100
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>> Finally, while following the involved code paths, I noted a check that 
>> is made in __ioremap, by calling
>> is_local_lowmem(). It would seem to me that calling this function just 
>> for the first address is insufficient - the range
>> specified may begin in non-lowmem but end in lowmem. Or it may begin 
>> in lowmem and end in non-lowmem, in which case I
>> would think that virt_to_page() wouldn't work correctly anymore 
>> (permitting, say, an erroneous dd command issued by root
>> to result in an oops or maybe worse things).
>
>It's assumed people using those interfaces know what they're doing. How 
>can a 'dd' end up in __ioremap() anyway?

/dev/mem's read/write handlers call ioremap...

Jan

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