Re: [edk2-devel] [edk2-platforms PATCH] Marvell/RealTimeClockLib: Allow only Unix Epoch in LibSetWakeupTime

["Laszlo Ersek" <lersek@redhat.com>]

On 12/21/20 21:09, Laszlo Ersek wrote:
> Hi Marcin,
> 
> On 12/21/20 17:37, Marcin Wojtas wrote:
>> Because the Armada RTC uses a 32-bit counter for seconds,
>> the maximum time span is just over 136 years.
>> Time is stored in Unix Epoch format, so it starts in 1970,
>> Therefore it can not exceed the year 2106.
>>
>> The issue emerged during ACS test case, which does not pass
>> Unix Epoch-relative time and caused EfiTimeToEpoch to assert.
>>
>> Signed-off-by: Marcin Wojtas <mw@semihalf.com>
>> ---
>>  Silicon/Marvell/Armada7k8k/Library/RealTimeClockLib/RealTimeClockLib.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/Silicon/Marvell/Armada7k8k/Library/RealTimeClockLib/RealTimeClockLib.c b/Silicon/Marvell/Armada7k8k/Library/RealTimeClockLib/RealTimeClockLib.c
>> index a811fd368e..40ab01ed41 100644
>> --- a/Silicon/Marvell/Armada7k8k/Library/RealTimeClockLib/RealTimeClockLib.c
>> +++ b/Silicon/Marvell/Armada7k8k/Library/RealTimeClockLib/RealTimeClockLib.c
>> @@ -179,6 +179,16 @@ LibSetWakeupTime (
>>  {
>>    UINTN       WakeupSeconds;
>>  
>> +  //
>> +  // Because the Armada RTC uses a 32-bit counter for seconds,
>> +  // the maximum time span is just over 136 years.
>> +  // Time is stored in Unix Epoch format, so it starts in 1970,
>> +  // Therefore it can not exceed the year 2106.
>> +  //
>> +  if ((Time->Year < 1970) || (Time->Year >= 2106)) {
>> +    return EFI_UNSUPPORTED;
>> +  }
>> +
>>    // Convert time to raw seconds
>>    WakeupSeconds = EfiTimeToEpoch (Time);
>>    if (WakeupSeconds > MAX_UINT32) {
>>
> 
> please see:
> 
> - edk2-platforms commit fbdfe8c4100d ("Silicon/Marvell/RealTimeClockLib:
> make EpochSeconds, WakeupSeconds UINTN", 2020-12-21) -- part of this is
> already visible in the context above,
> 
> - edk2 commit c06635ea3f4b ("EmbeddedPkg/TimeBaseLib: remove useless
> truncation to 32-bit", 2020-12-21).
> 
> If you advance the edk2 submodule reference in edk2-platforms to or past
> c06635ea3f4b, then the "Time->Year >= 2106" condition will be covered
> already, by the (WakeupSeconds > MAX_UINT32) check.

(Oops, sorry, I forgot that edk2-platforms consumes edk2 *only* through PACKAGES_PATH, and never through a submodule; so please adjust the above submodule statement accordingly.)

BTW, is this library instance ever built for 32-bit ARM? Because in that case (== UINTN meaning UINT32), checking Year against 2106 makes sense as well. While build-testing the above-noted patches, I tried to build them for 32-bit ARM too, but that arch did not seem applicable: while the following command works:

  build \
    -a AARCH64 \
    -b NOOPT \
    -p Platform/SolidRun/Armada80x0McBin/Armada80x0McBin.dsc \
    -t GCC5 \
    -m EmbeddedPkg/RealTimeClockRuntimeDxe/RealTimeClockRuntimeDxe.inf

the same with "-a ARM" fails, with the following error message:

edk2-platforms/Platform/SolidRun/Armada80x0McBin/Armada80x0McBin.dsc(...): error 4000: Instance of library class [ArmSoftFloatLib] is not found
        in [edk2/CryptoPkg/Library/OpensslLib/OpensslLib.inf] [ARM]
        consumed by module [edk2/SignedCapsulePkg/Universal/SystemFirmwareUpdate/SystemFirmwareReportDxe.inf]

which implies that "Armada80x0McBin.dsc" is never actually built for ARM.

... Hm, the following platforms:

- Platform/Marvell/Armada80x0Db/Armada80x0Db.dsc
- Platform/Marvell/Armada70x0Db/Armada70x0Db.dsc

do build the library for ARM. So this patch seems justified after all, as-posted (i.e., including the year 2106 check).

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo

> 
> Preventing ASSERT (JulianDate >= EPOCH_JULIAN_DATE) from firing in
> EfiGetEpochDays() still makes sense, so the (Time->Year < 1970) check
> can still be added usefully, I think.
> 
> Thanks
> Laszlo
>