linux-kernel - Re: [PATCH 1/1] x86: add phys addr validity check for /dev/mem mmap

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Message-ID: <53ECEFF5.1040800@zytor.com>
Date:	Thu, 14 Aug 2014 10:20:53 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Dave Hansen <dave.hansen@...el.com>,
	Frantisek Hrbata <fhrbata@...hat.com>,
	linux-kernel@...r.kernel.org
CC:	linux-mm@...ck.org, tglx@...utronix.de, mingo@...hat.com,
	x86@...nel.org, oleg@...hat.com, kamaleshb@...ibm.com,
	hechjie@...ibm.com, akpm@...ux-foundation.org, dvlasenk@...hat.com,
	prarit@...hat.com, lwoodman@...hat.com, hannsj_uhl@...ibm.com
Subject: Re: [PATCH 1/1] x86: add phys addr validity check for /dev/mem mmap

On 08/14/2014 09:36 AM, Dave Hansen wrote:
> Thanks for dredging this back up!
> 
> On 08/14/2014 07:18 AM, Frantisek Hrbata wrote:
>> +int valid_phys_addr_range(phys_addr_t addr, size_t count)
>> +{
>> +	return addr + count <= __pa(high_memory);
>> +}
> 
> Is this correct on 32-bit?  It would limit /dev/mem to memory below 896MB.
> 

Last I checked, /dev/mem was already broken for highmem... which is
actually a problem.  I would prefer to see it fixed.

	-hpa

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