Re: [PATCH 2/2] x86/boot: increase maximum number of avoided KASLR regions
From: Julian Stecklina
Date: Wed Feb 06 2019 - 07:51:15 EST
Borislav Petkov <bp@xxxxxxxxx> writes:
>> @@ -213,7 +213,7 @@ static void mem_avoid_memmap(char *str)
>> i++;
>> }
>>
>> - /* More than 4 memmaps, fail kaslr */
>> + /* Can't store all regions, fail kaslr */
>> if ((i >= MAX_MEMMAP_REGIONS) && str)
>> memmap_too_large = true;
>> }
>> --
>
> Lemme add some of the folks from
> f28442497b5caf7bf573ade22a7f8d3559e3ef56 to Cc.
>
> It all looks arbitrary to me: first 4 unusable memmap regions, this
> patch raises it to 16. Why are we even imposing such a limit?
Because at this point, we are not in a good position to handle an
unlimited amount of regions.
As for the choice of "16", I took our usecase and multiplied it by two.
FWIW, this could be even larger.
Julian