linux-kernel - Re: [PATCH v1 1/1] pstore/ram: Fix crash when setting number of cpus to an odd number

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Date:   Fri, 24 Feb 2023 11:07:47 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Weichen Chen <weichen.chen@...iatek.com>,
        linux-hardening@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, yt.shen@...iatek.com,
        angelogioacchino.delregno@...labora.com, tony.luck@...el.com,
        keescook@...omium.org, darren.chen@...iatek.com
Subject: Re: [PATCH v1 1/1] pstore/ram: Fix crash when setting number of cpus
 to an odd number



On 24/02/2023 05:00, Guilherme G. Piccoli wrote:
> On 23/02/2023 23:36, Weichen Chen wrote:
>> When the number of cpu cores is adjusted to 7 or other odd numbers,
>> the zone size will become an odd number.
>> The address of the zone will become:
>>      addr of zone0 = BASE
>>      addr of zone1 = BASE + zone_size
>>      addr of zone2 = BASE + zone_size*2
>>      ...
>> The address of zone1/3/5/7 will be mapped to non-alignment va.
>> Eventually crashes will occur when accessing these va.
>>
>> So, use ALIGN_DOWN() to make sure the zone size is even
>> to avoid this bug.
>>
>> Signed-off-by: Weichen Chen <weichen.chen@...iatek.com>
>> ---
>>   fs/pstore/ram.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
>> index ade66dbe5f39..fc57ac97e506 100644
>> --- a/fs/pstore/ram.c
>> +++ b/fs/pstore/ram.c
>> @@ -528,6 +528,7 @@ static int ramoops_init_przs(const char *name,
>>   	}
>>   
>>   	zone_sz = mem_sz / *cnt;
>> +	zone_sz = ALIGN_DOWN(zone_sz, 2);
>>   	if (!zone_sz) {
>>   		dev_err(dev, "%s zone size == 0\n", name);
>>   		goto fail;
> 
> Thanks for resending! Feel free to add my:
> 
> Tested-by: Guilherme G. Piccoli <gpiccoli@...lia.com>
> 

Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>

I gave that yesterday, but Weichen Chen seems to have forgotten about it.

Regards,
Matthias