On 03/07/18 10:42, Zeng, Star wrote:
> Hi Laszlo,
>
> Good analysis.
>
> Yes, the SupportedHashMask field in HashInterfaceHob will have stale value,
> but that does not impact the functionality since the code have.
> So the patch could fix the problem.
>
> HashLibBaseCryptoRouterPeiConstructor():
> Status = PcdSet32S (PcdTcg2HashAlgorithmBitmap, 0);
>
> RegisterHashInterfaceLib():
> HashInterfaceHob->SupportedHashMask = PcdGet32 (PcdTcg2HashAlgorithmBitmap)
> | HashMask;
>
> HashStart()/HashUpdate()/HashCompleteAndExtend()/HashAndExtend():
> if (HashInterfaceHob->HashInterfaceCount == 0) {
> return EFI_UNSUPPORTED;
> }
>
> RegisterHashInterfaceLib():
> if (HashInterfaceHob->HashInterfaceCount >= HASH_COUNT) {
> return EFI_OUT_OF_RESOURCES;
> }
Ugh, this is a bit too complex for me to digest right now, but I'll
trust you if you say the value doesn't matter :)
> As I know, Chao has helped push the patch.
Yes, that's correct, it's commit 4cc2b63bd829 ("SecurityPkg: only clear
HashInterface information", 2018-03-07).
> But I am fine with keeping this patch or continue refining the code. :)
I would slightly prefer clearing the SupportedHashMask field as well (or
adding a comment explaining why it's not necessary), because then the
uninitiated reader, like me, wouldn't have to ask themselves why the
field isn't being cleared :)
But, given your response, I don't feel strongly about it any longer;
I'll leave it up to Marc-André.
(Also, if we have to choose between extending the ZeroMem() and writing
the comment, I think the former is easier :) I could write that too, but
I couldn't write the comment.)
> Is it working with " ZeroMem (HashInterfaceHob, sizeof (*HashInterfaceHob) -
> sizeof (EFI_GUID)) " if to refine the code?
I'll skip this question based on your later followup.
Thanks!
Laszlo
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