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

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

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.

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