linux-kernel - Re: Regression from efi: call get_event

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Date:   Mon, 12 Mar 2018 14:30:05 +0000
From:   Jeremy Cline <jeremy@...ine.org>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Thiebaud Weksteen <tweek@...gle.com>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Regression from efi: call get_event_log before ExitBootServices

On 03/12/2018 07:08 AM, Ard Biesheuvel wrote:
> On 10 March 2018 at 10:45, Thiebaud Weksteen <tweek@...gle.com> wrote:
>> On Fri, Mar 9, 2018 at 5:54 PM Jeremy Cline <jeremy@...ine.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.

Regards,
Jeremy