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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Mon, 12 Mar 2018 14:56:08 +0000
Message-ID: <CAKv+Gu8+x=5nU9MmYQKKc=3fhMXoUYjGSjYYfhjaFtdGG2NkaA@mail.gmail.com>
Subject: Re: Regression from efi: call get_event_log before ExitBootServices
To:     Jeremy Cline <jeremy@jcline.org>
Cc:     Thiebaud Weksteen <tweek@google.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        linux-efi@vger.kernel.org, linux-integrity@vger.kernel.org,
        tpmdd-devel@lists.sourceforge.net,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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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)

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