linux-kernel - Re: [PATCH] x86/acpi: check rsdp address received via bootparams to be valid

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Date:   Wed, 17 Jan 2018 13:20:01 +0100
From:   Juergen Gross <jgross@...e.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] x86/acpi: check rsdp address received via bootparams to
 be valid

On 17/01/18 12:49, Rafael J. Wysocki wrote:
> On Tue, Jan 16, 2018 at 2:57 PM, Juergen Gross <jgross@...e.com> wrote:
>> There seem to exist several grub2 versions trashing
>> boot_params.hdr.acpi_rsdp_addr.
>>
>> So don't just believe this address to be valid, but verify it pointing
>> to a valid RSDP table.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>> To be applied on top of my RSDP series currently in tip.git x86/boot
>> Mike Galbraith has tested this patch to repair his broken boot
>> ---
>>  drivers/acpi/acpica/tbxfroot.c | 36 ++++++++++++++++++++++++++++++++++++
>>  drivers/acpi/osl.c             |  2 +-
>>  include/acpi/acpixf.h          |  5 +++++
>>  3 files changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/acpica/tbxfroot.c b/drivers/acpi/acpica/tbxfroot.c
>> index f9f9a7da2cad..9edc71780a38 100644
>> --- a/drivers/acpi/acpica/tbxfroot.c
>> +++ b/drivers/acpi/acpica/tbxfroot.c
>> @@ -249,6 +249,42 @@ ACPI_EXPORT_SYMBOL_INIT(acpi_find_root_pointer)
>>
>>  /*******************************************************************************
>>   *
>> + * FUNCTION:    acpi_verify_root_pointer
> 
> Why do you want this to go into ACPICA?

It seemed to fit in here.

>> + *
>> + *
>> + * PARAMETERS:  rsdp_address        - Pointer to suspected RSDP
>> + *
>> + * RETURN:      AE_OK if rsdp_address really points to a RSDP, AE_NOT_FOUND
>> + *              else
>> + *
>> + * DESCRIPTION: Verify a physical address being a valid RSDP
>> + *
>> + ******************************************************************************/
>> +
>> +acpi_status ACPI_INIT_FUNCTION
>> +acpi_verify_root_pointer(acpi_physical_address rsdp_address)
>> +{
>> +       acpi_status status;
>> +       struct acpi_table_rsdp *rsdp;
>> +
>> +       ACPI_FUNCTION_TRACE(acpi_verify_root_pointer);
>> +
>> +       rsdp = acpi_os_map_memory(rsdp_address, sizeof(*rsdp));
>> +
>> +       if (!rsdp)
>> +               return_ACPI_STATUS(AE_NO_MEMORY);
>> +
>> +       status = acpi_tb_validate_rsdp(rsdp);
>> +
>> +       acpi_os_unmap_memory(rsdp, sizeof(*rsdp));
>> +
>> +       return_ACPI_STATUS(status);
>> +}
>> +
>> +ACPI_EXPORT_SYMBOL_INIT(acpi_verify_root_pointer)
>> +
>> +/*******************************************************************************
>> + *
>>   * FUNCTION:    acpi_tb_scan_memory_for_rsdp
>>   *
>>   * PARAMETERS:  start_address       - Starting pointer for search
>> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
>> index 2b77db914752..facff5c11f32 100644
>> --- a/drivers/acpi/osl.c
>> +++ b/drivers/acpi/osl.c
>> @@ -201,7 +201,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
>>                 return acpi_rsdp;
>>  #endif
>>         pa = acpi_arch_get_root_pointer();
>> -       if (pa)
>> +       if (pa && acpi_verify_root_pointer(pa) == AE_OK)
> 
> All things needed could just be done locally in this file.

Okay, if you prefer it this way I can move acpi_verify_root_pointer() to
osl.c.


Juergen