linux-kernel - Re: [PATCH 1/2] x86: fix panic when handling "mem={invalid}" param

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Date:	Fri, 04 Feb 2011 12:09:05 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Kamal Mostafa <kamal@...onical.com>, x86@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Len Brown <len.brown@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86: fix panic when handling "mem={invalid}" param

On 02/04/2011 11:44 AM, Yinghai Lu wrote:
> On Thu, Feb 3, 2011 at 5:38 PM, Kamal Mostafa <kamal@...onical.com> wrote:
>> Avoid removing all of memory and panicing when "mem={invalid}" is
>> specified, e.g. mem=blahblah, mem=0, or mem=nopentium (on platforms
>> other than x86_32).
>>
>> BugLink: http://bugs.launchpad.net/bugs/553464
>> Signed-off-by: Kamal Mostafa <kamal@...onical.com>
>> Cc: <stable@...nel.org>
>> ---
>>  arch/x86/kernel/e820.c |    3 +++
>>  1 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
>> index 294f26d..55a59d8 100644
>> --- a/arch/x86/kernel/e820.c
>> +++ b/arch/x86/kernel/e820.c
>> @@ -856,6 +856,9 @@ static int __init parse_memopt(char *p)
>>
>>        userdef = 1;
>>        mem_size = memparse(p, &p);
>> +       /* don't remove all of memory when handling "mem={invalid}" param */
>> +       if (mem_size == 0)
>> +               return -EINVAL;
>>        e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
>>
>>        return 0;
>> --
> 
> then how about some one pass mem=32M etc?
> 
> or total wrongly usermap?
> 

All he looks at is when the value returned is zero.  It wouldn't be zero
for any actual value, including mem=32M.

	-hpa
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