Re: [PATCH] SecurityPkg/Tpm2Help.c: Add boundary check for array

["Zhang, Shenglei" <shenglei.zhang@intel.com>]

> -----Original Message-----
> From: Yao, Jiewen
> Sent: Friday, December 6, 2019 10:04 AM
> To: Zhang, Shenglei <shenglei.zhang@intel.com>; devel@edk2.groups.io
> Cc: Wang, Jian J <jian.j.wang@intel.com>; Zhang, Chao B
> <chao.b.zhang@intel.com>
> Subject: RE: [PATCH] SecurityPkg/Tpm2Help.c: Add boundary check for array
> 
> Hi
> May I know where is the data from? Trusted region or non-trusted region?
> 
> I am thinking if we need use ASSERT to avoid user mistake.
> But want to check the API input assumption at first...

Hi Jiewen,

I don't think DigestList->count can be trusted. We can add Index < HASH_COUNT into the
for(...) statement.

Thanks,
Shenglei

> 
> 
> 
> > -----Original Message-----
> > From: Zhang, Shenglei <shenglei.zhang@intel.com>
> > Sent: Friday, December 6, 2019 9:50 AM
> > To: devel@edk2.groups.io
> > Cc: Yao, Jiewen <jiewen.yao@intel.com>; Wang, Jian J
> <jian.j.wang@intel.com>;
> > Zhang, Chao B <chao.b.zhang@intel.com>
> > Subject: [PATCH] SecurityPkg/Tpm2Help.c: Add boundary check for array
> >
> > Add 'Index < HASH_COUNT' to ensure things out of boundary
> > of digests[] can not be visited.
> >
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Jian J Wang <jian.j.wang@intel.com>
> > Cc: Chao Zhang <chao.b.zhang@intel.com>
> > Signed-off-by: Shenglei Zhang <shenglei.zhang@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;
> >    }
> > --
> > 2.18.0.windows.1