[PATCH v2] riscv: define ILLEGAL_POINTER_VALUE for 64bit

[Palmer Dabbelt]

On Fri, 05 Jul 2024 17:50:10 PDT (-0700), jszhang at kernel.org wrote:
> On Sat, Jul 06, 2024 at 01:02:10AM +0800, Jisheng Zhang wrote:
>> This is used in poison.h for poison pointer offset. Based on current
>> SV39, SV48 and SV57 vm layout, 0xdead000000000000 is a proper value
>> that is not mappable, this can avoid potentially turning an oops to
>> an expolit.
>
> Maybe I also need to cc stable? This is a secure hole fix patch.

Ya, and I guess it's just been broken forever?  I stuck a

Fixes: fbe934d69eb7 ("RISC-V: Build Infrastructure")

it should show up on for-next, assuming the tests pass...

>
>>
>> Signed-off-by: Jisheng Zhang <jszhang at kernel.org>
>> ---
>>
>> Since v1:
>>  - fix typo:s/SV59/SV57
>>
>>  arch/riscv/Kconfig | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index c51b32a8ddff..c992eabbd002 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -313,6 +313,11 @@ config GENERIC_HWEIGHT
>>  config FIX_EARLYCON_MEM
>>  	def_bool MMU
>>
>> +config ILLEGAL_POINTER_VALUE
>> +	hex
>> +	default 0 if 32BIT
>> +	default 0xdead000000000000 if 64BIT
>> +
>>  config PGTABLE_LEVELS
>>  	int
>>  	default 5 if 64BIT
>> --
>> 2.43.0
>>
>>
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