On 12/06/19 02:49, Zhang, Shenglei wrote:
> Add 'Index < HASH_COUNT' to ensure things out of boundary
> of digests[] can not be visited.
>
> Cc: Jiewen Yao <jiewen....@intel.com>
> Cc: Jian J Wang <jian.j.w...@intel.com>
> Cc: Chao Zhang <chao.b.zh...@intel.com>
> Signed-off-by: Shenglei Zhang <shenglei.zh...@intel.com>
> ---
> SecurityPkg/Library/Tpm2CommandLib/Tpm2Help.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Help.c
> b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Help.c
> index 36c240d1221c..a7d4e3ab5373 100644
> --- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Help.c
> +++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Help.c
> @@ -299,7 +299,7 @@ GetDigestListSize (
> UINT32 TotalSize;
>
> TotalSize = sizeof(DigestList->count);
> - for (Index = 0; Index < DigestList->count; Index++) {
> + for (Index = 0; Index < DigestList->count, Index < HASH_COUNT; Index++) {
> DigestSize = GetHashSizeFromAlgo (DigestList->digests[Index].hashAlg);
> TotalSize += sizeof(DigestList->digests[Index].hashAlg) + DigestSize;
> }
>
Nacked-by: Laszlo Ersek <ler...@redhat.com>
The comma operator is either functionally wrong in this context, or
stylistically wrong. From the C standard:
The left operand of a comma operator is evaluated as a void
expression; there is a sequence point after its evaluation. Then the
right operand is evaluated; the result has its type and value. [...]
In case we *only* need to check (Index < HASH_COUNT), then the patch is
stylistically incorrect: the (Index < DigestList->count) condition
should simply be removed.
In case we need to check *both* conditions, then the patch is
functionally wrong: we should either use the logical AND (&&) operator,
instead of the comma:
Index < DigestList->count && Index < HASH_COUNT
or invoke the MIN() function-like macro:
Index < MIN ((UINTN)DigestList->count, (UINTN)HASH_COUNT)
Thanks
Laszlo
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