Re: [PATCH] x86/boot: clear rsdp address in boot_params for broken loaders

[Juergen Gross]

On 04/12/2018 00:07, hpa@xxxxxxxxx wrote:
> On December 3, 2018 2:38:11 AM PST, Juergen Gross <jgross@xxxxxxxx> wrote:
>> In case a broken boot loader doesn't clear its struct boot_params clear
>> rsdp_addr in sanitize_boot_params().
>>
>> This fixes commit e6e094e053af75 ("x86/acpi, x86/boot: Take RSDP
>> address from boot params if available") e.g. for the case of a boot via
>> systemd-boot.
>>
>> Fixes: e6e094e053af75 ("x86/acpi, x86/boot: Take RSDP address from boot
>> params if available")
>> Reported-by: Gunnar Krueger <taijian@xxxxxxxxx>
>> Tested-by: Gunnar Krueger <taijian@xxxxxxxxx>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> ---
>> arch/x86/include/asm/bootparam_utils.h | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/x86/include/asm/bootparam_utils.h
>> b/arch/x86/include/asm/bootparam_utils.h
>> index a07ffd23e4dd..f6f6ef436599 100644
>> --- a/arch/x86/include/asm/bootparam_utils.h
>> +++ b/arch/x86/include/asm/bootparam_utils.h
>> @@ -36,6 +36,7 @@ static void sanitize_boot_params(struct boot_params
>> *boot_params)
>> 	 */
>> 	if (boot_params->sentinel) {
>> 		/* fields in boot_params are left uninitialized, clear them */
>> +		boot_params->acpi_rsdp_addr = 0;
>> 		memset(&boot_params->ext_ramdisk_image, 0,
>> 		       (char *)&boot_params->efi_info -
>> 			(char *)&boot_params->ext_ramdisk_image);
> 
> Isn't this already covered by the memset()? If not, we should extend the memset() to maximal coverage.

I'd like to send a followup patch doing that. And I'd like to not only
test sentinel for being non-zero, but all padding fields as well. This
should be 4.21 material, though.


Juergen