Re: Regression from efi: call get_event_log before ExitBootServices

[Thiebaud Weksteen <tweek@google.com>]

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).