Re: [edk2-devel] [PATCH v1 04/12] CryptoPkg: Fix conditionally uninitialized variable

["Michael Kubacki" <mikuback@linux.microsoft.com>]

Thanks. I'll make the suggested change in the v2 series.

On 11/23/2022 8:37 PM, Michael D Kinney wrote:
> Hi Michael,
> 
> Comments below.
> 
> Mike
> 
>> -----Original Message-----
>> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Michael Kubacki
>> Sent: Wednesday, November 9, 2022 9:33 AM
>> To: devel@edk2.groups.io
>> Cc: Erich McMillan <emcmillan@microsoft.com>; Jiang, Guomin <guomin.jiang@intel.com>; Wang, Jian J
>> <jian.j.wang@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Michael Kubacki <mikuback@linux.microsoft.com>; Lu, Xiaoyu1
>> <xiaoyu1.lu@intel.com>
>> Subject: [edk2-devel] [PATCH v1 04/12] CryptoPkg: Fix conditionally uninitialized variable
>>
>> From: Michael Kubacki <michael.kubacki@microsoft.com>
>>
>> Fixes CodeQL alerts for CWE-457:
>> https://cwe.mitre.org/data/definitions/457.html
>>
>> Checks the return value from `ASN1_get_object()` to verify values
>> set by the function are valid.
>>
>> Note that the function returns literal `0x80`:
>>      `return (0x80);`
>>
>> That is used to check the return value is as the case in other areas
>> of the code.
>>
>> Cc: Erich McMillan <emcmillan@microsoft.com>
>> Cc: Guomin Jiang <guomin.jiang@intel.com>
>> Cc: Jian J Wang <jian.j.wang@intel.com>
>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>> Cc: Michael Kubacki <mikuback@linux.microsoft.com>
>> Cc: Xiaoyu Lu <xiaoyu1.lu@intel.com>
>> Co-authored-by: Erich McMillan <emcmillan@microsoft.com>
>> Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
>> ---
>>   CryptoPkg/Library/BaseCryptLib/Pk/CryptX509.c | 21 +++++++++++---------
>>   1 file changed, 12 insertions(+), 9 deletions(-)
>>
>> diff --git a/CryptoPkg/Library/BaseCryptLib/Pk/CryptX509.c b/CryptoPkg/Library/BaseCryptLib/Pk/CryptX509.c
>> index 2333157e0d17..f867656e888c 100644
>> --- a/CryptoPkg/Library/BaseCryptLib/Pk/CryptX509.c
>> +++ b/CryptoPkg/Library/BaseCryptLib/Pk/CryptX509.c
>> @@ -807,6 +807,7 @@ X509GetTBSCert (
>>     UINT32       Asn1Tag;
>>     UINT32       ObjClass;
>>     UINTN        Length;
>> +  UINTN        Inf;
>>
>>     //
>>     // Check input parameters.
>> @@ -836,9 +837,9 @@ X509GetTBSCert (
>>     //
>>     Temp   = Cert;
>>     Length = 0;
>> -  ASN1_get_object (&Temp, (long *)&Length, (int *)&Asn1Tag, (int *)&ObjClass, (long)CertSize);
>> +  Inf    = ASN1_get_object (&Temp, (long *)&Length, (int *)&Asn1Tag, (int *)&ObjClass, (long)CertSize);
>>
>> -  if (Asn1Tag != V_ASN1_SEQUENCE) {
>> +  if (!(Inf & 0x80) && (Asn1Tag != V_ASN1_SEQUENCE)) {
> 
> The result of bitwise operation (Inf & 0x80) is a value, not a BOOLEAN.
> I think the more correct way to do this check is ((Inf & 0x80) == 0x00).
> 
>>       return FALSE;
>>     }
>>
>> @@ -848,7 +849,7 @@ X509GetTBSCert (
>>     //
>>     // Verify the parsed TBSCertificate is one correct SEQUENCE data.
>>     //
>> -  if (Asn1Tag != V_ASN1_SEQUENCE) {
>> +  if (!(Inf & 0x80) && (Asn1Tag != V_ASN1_SEQUENCE)) {
> 
> The result of bitwise operation (Inf & 0x80) is a value, not a BOOLEAN.
> I think the more correct way to do this check is ((Inf & 0x80) == 0x00).
> 
>>       return FALSE;
>>     }
>>
>> @@ -1888,18 +1889,20 @@ Asn1GetTag (
>>     IN     UINT32   Tag
>>     )
>>   {
>> -  UINT8  *PtrOld;
>> -  INT32  ObjTag;
>> -  INT32  ObjCls;
>> -  long   ObjLength;
>> +  UINT8   *PtrOld;
>> +  INT32   ObjTag;
>> +  INT32   ObjCls;
>> +  long    ObjLength;
>> +  UINT32  Inf;
>>
>>     //
>>     // Save Ptr position
>>     //
>>     PtrOld = *Ptr;
>>
>> -  ASN1_get_object ((CONST UINT8 **)Ptr, &ObjLength, &ObjTag, &ObjCls, (INT32)(End - (*Ptr)));
>> -  if ((ObjTag == (INT32)(Tag & CRYPTO_ASN1_TAG_VALUE_MASK)) &&
>> +  Inf = ASN1_get_object ((CONST UINT8 **)Ptr, &ObjLength, &ObjTag, &ObjCls, (INT32)(End - (*Ptr)));
>> +  if (!(Inf & 0x80) &&
> 
> The result of bitwise operation (Inf & 0x80) is a value, not a BOOLEAN.
> I think the more correct way to do this check is ((Inf & 0x80) == 0x00).
> 
>> +      (ObjTag == (INT32)(Tag & CRYPTO_ASN1_TAG_VALUE_MASK)) &&
>>         (ObjCls == (INT32)(Tag & CRYPTO_ASN1_TAG_CLASS_MASK)))
>>     {
>>       *Length = (UINTN)ObjLength;
>> --
>> 2.28.0.windows.1
>>
>>
>>
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