Re: Regression from efi: call get_event_log before ExitBootServices

[Jeremy Cline <jeremy@jcline.org>]

On 03/12/2018 02:29 PM, Thiebaud Weksteen wrote:
> On Mon, Mar 12, 2018 at 6:30 PM Ard Biesheuvel <ard.biesheuvel@linaro.org>
> wrote:
> 
>> On 12 March 2018 at 17:01, Jeremy Cline <jeremy@jcline.org> wrote:
>>> On 03/12/2018 10:56 AM, Ard Biesheuvel wrote:
>>>> On 12 March 2018 at 14:30, Jeremy Cline <jeremy@jcline.org> wrote:
>>>>> On 03/12/2018 07:08 AM, Ard Biesheuvel wrote:
>>>>>> On 10 March 2018 at 10:45, Thiebaud Weksteen <tweek@google.com>
> wrote:
>>>>>>> On Fri, Mar 9, 2018 at 5:54 PM Jeremy Cline <jeremy@jcline.org>
> wrote:
>>>>>>>
>>>>>>>> On Fri, Mar 09, 2018 at 10:43:50AM +0000, Thiebaud Weksteen wrote:
>>>>>>>>> Thanks a lot for trying out the patch!
>>>>>>>>>
>>>>>>>>> Please don't modify your install at this stage, I think we are
> hitting a
>>>>>>>>> firmware bug and that would be awesome if we can fix how we are
>>>>>>> handling it.
>>>>>>>>> So, if we reach that stage in the function it could either be
> that:
>>>>>>>>> * The allocation did not succeed, somehow, but the firmware still
>>>>>>> returned
>>>>>>>>> EFI_SUCCEED.
>>>>>>>>> * The size requested is incorrect (I'm thinking something like a
> 1G of
>>>>>>>>> log). This would be due to either a miscalculation of log_size
>>>>>>> (possible)
>>>>>>>>> or; the returned values of GetEventLog are not correct.
>>>>>>>>> I'm sending a patch to add checks for these. Could you please
> apply and
>>>>>>>>> retest?
>>>>>>>>> Again, thanks for helping debugging this.
>>>>>>>
>>>>>>>> No problem, thanks for the help :)
>>>>>>>
>>>>>>>> With the new patch:
>>>>>>>
>>>>>>>> Locating the TCG2Protocol
>>>>>>>> Calling GetEventLog on TCG2Protocol
>>>>>>>> Log returned
>>>>>>>> log_location is not empty
>>>>>>>> log_size != 0
>>>>>>>> log_size < 1M
>>>>>>>> Allocating memory for storing the logs
>>>>>>>> Returned from memory allocation
>>>>>>>> Copying log to new location
>>>>>>>
>>>>>>>> And then it hangs. I added a couple more print statements:
>>>>>>>
>>>>>>>> diff --git a/drivers/firmware/efi/libstub/tpm.c
>>>>>>> b/drivers/firmware/efi/libstub/tpm.c
>>>>>>>> index ee3fac109078..1ab5638bc50e 100644
>>>>>>>> --- a/drivers/firmware/efi/libstub/tpm.c
>>>>>>>> +++ b/drivers/firmware/efi/libstub/tpm.c
>>>>>>>> @@ -148,8 +148,11 @@ void
>>>>>>> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>>>>>>>>          efi_printk(sys_table_arg, "Copying log to new
> location\n");
>>>>>>>
>>>>>>>>          memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
>>>>>>>> +       efi_printk(sys_table_arg, "Successfully memset log_tbl to
> 0\n");
>>>>>>>>          log_tbl->size = log_size;
>>>>>>>> +       efi_printk(sys_table_arg, "Set log_tbl->size\n");
>>>>>>>>          log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
>>>>>>>> +       efi_printk(sys_table_arg, "Set log_tbl-version\n");
>>>>>>>>          memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
>>>>>>>
>>>>>>>>          efi_printk(sys_table_arg, "Installing the log into the
>>>>>>> configuration table\n");
>>>>>>>
>>>>>>>> and it's hanging at "memset(log_tbl, 0, sizeof(*log_tbl) +
> log_size);"
>>>>>>>
>>>>>>> Thanks. Well, it looks like the memory that is supposedly allocated
> is not
>>>>>>> usable. I'm thinking this is a firmware bug.
>>>>>>> Ard, would you agree on this assumption? Thoughts on how to proceed?
>>>>>>>
>>>>>>
>>>>>> I am rather puzzled why the allocate_pool() should succeed and the
>>>>>> subsequent memset() should fail. This does not look like an issue
> that
>>>>>> is intimately related to TPM2 support, rather an issue in the
> firmware
>>>>>> that happens to get tickled after the change.
>>>>>>
>>>>>> Would you mind trying replacing EFI_LOADER_DATA with
>>>>>> EFI_BOOT_SERVICES_DATA in the allocate_pool() call?
>>>>>
>>>>> Replacing EFI_LOADER_DATA with EFI_BOOT_SERVICES_DATA still hangs at
> the
>>>>> memset() call.
>>>>>
>>>>
>>>> Could you try the following please? (attached as well in case gmail
> mangles it)
>>>>
>>>> diff --git a/drivers/firmware/efi/libstub/tpm.c
>>>> b/drivers/firmware/efi/libstub/tpm.c
>>>> index 2298560cea72..30d960a344b7 100644
>>>> --- a/drivers/firmware/efi/libstub/tpm.c
>>>> +++ b/drivers/firmware/efi/libstub/tpm.c
>>>> @@ -70,6 +70,8 @@ void
>>>> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>>>>         size_t log_size, last_entry_size;
>>>>         efi_bool_t truncated;
>>>>         void *tcg2_protocol;
>>>> +       unsigned long num_pages;
>>>> +       efi_physical_addr_t log_tbl_alloc;
>>>>
>>>>         status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
>>>>                                 &tcg2_protocol);
>>>> @@ -104,9 +106,12 @@ void
>>>> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>>>>         }
>>>>
>>>>         /* Allocate space for the logs and copy them. */
>>>> -       status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
>>>> -                               sizeof(*log_tbl) + log_size,
>>>> -                               (void **) &log_tbl);
>>>> +       num_pages = DIV_ROUND_UP(sizeof(*log_tbl) + log_size,
> EFI_PAGE_SIZE);
>>>> +       status = efi_call_early(allocate_pages,
>>>> +                               EFI_ALLOCATE_ANY_PAGES,
>>>> +                               EFI_LOADER_DATA,
>>>> +                               num_pages,
>>>> +                               &log_tbl_alloc);
>>>>
>>>>         if (status != EFI_SUCCESS) {
>>>>                 efi_printk(sys_table_arg,
>>>> @@ -114,6 +119,7 @@ void
>>>> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>>>>                 return;
>>>>         }
>>>>
>>>> +       log_tbl = (struct linux_efi_tpm_eventlog *)(unsigned
> long)log_tbl_alloc;
>>>>         memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
>>>>         log_tbl->size = log_size;
>>>>         log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
>>>> @@ -126,7 +132,7 @@ void
>>>> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>>>>         return;
>>>>
>>>>  err_free:
>>>> -       efi_call_early(free_pool, log_tbl);
>>>> +       efi_call_early(free_pages, log_tbl_alloc, num_pages);
>>>>  }
>>>>
>>>>  void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
>>>>
>>>
>>> Hi Ard,
>>>
>>> When I apply this, it starts hanging at
>>>
>>> status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
>>>                         EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
>>>                         &log_location, &log_last_entry, &truncated);
>>>
>>> rather than at the memset() call.
>>>
> 
>> That is *very* surprising, given that the change only affects code
>> that executes after that.
> 
>> I understand how annoying this is for you, and I think we should try
>> to fix this, but reverting the patches outright isn't the solution
>> either.
> 
>> Which UEFI vendor and version does your system report?
> 
> You should be able to find this info using the "ver" command in the UEFI
> shell.
> The UEFI vendor is Insyde (see first message).
> 

Ah, thanks!

EFI Specification Revision	: 2.40
EFI Vendor			: INSYDE Corp.
EFI Revision			: 21573.83

Regards,
Jeremy