[CodeQL] CryptoPkg: BaseCryptLib: Check return value from `ASN1_get_o…

…bject` (#470)

# Preface

Please ensure you have read the [contribution
docs](https://github.com/microsoft/mu/blob/master/CONTRIBUTING.md) prior
to submitting the pull request. In particular,
[pull request
guidelines](https://github.com/microsoft/mu/blob/master/CONTRIBUTING.md#pull-request-best-practices).

## Description

This change was caught on a platform build Code QL analysis. Without
properly checking the returned value, `ObjTag` and `ObjCls` could be
left uninitialized and thus cause incorrect results.

For each item, place an "x" in between `[` and `]` if true. Example:
`[x]`.
_(you can also check items in the GitHub UI)_

- [x] Impacts functionality?
- **Functionality** - Does the change ultimately impact how firmware
functions?
- Examples: Add a new library, publish a new PPI, update an algorithm,
...
- [x] Impacts security?
- **Security** - Does the change have a direct security impact on an
application,
    flow, or firmware?
  - Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
- [ ] Breaking change?
- **Breaking change** - Will anyone consuming this change experience a
break
    in build or boot behavior?
- Examples: Add a new library class, move a module to a different repo,
call
    a function in a new library class in a pre-existing module, ...
- [ ] Includes tests?
  - **Tests** - Does the change include any explicit test code?
  - Examples: Unit tests, integration tests, robot tests, ...
- [ ] Includes documentation?
- **Documentation** - Does the change contain explicit documentation
additions
    outside direct code modifications (and comments)?
- Examples: Update readme file, add feature readme file, link to
documentation
    on an a separate Web page, ...

## How This Was Tested

The change was tested on QEMU based virtual platform and proprietary
hardware platform.

## Integration Instructions

N/A

CryptoPkg/Library/BaseCryptLib/Pk/CryptX509.c

@@ -1908,12 +1908,25 @@ Asn1GetTag (
   INT32  ObjCls;
   long   ObjLength;
 
+  // MU_CHANGE [BEGIN] - CodeQL change
+  INT32  Ret;
+
+  // MU_CHANGE [END] - CodeQL change
+
   //
   // Save Ptr position
   //
   PtrOld = *Ptr;
 
-  ASN1_get_object ((CONST UINT8 **)Ptr, &ObjLength, &ObjTag, &ObjCls, (INT32)(End - (*Ptr)));
+  // MU_CHANGE [BEGIN] - CodeQL change
+  // ASN1_get_object ((CONST UINT8 **)Ptr, &ObjLength, &ObjTag, &ObjCls, (INT32)(End - (*Ptr)));
+  Ret = ASN1_get_object ((CONST UINT8 **)Ptr, &ObjLength, &ObjTag, &ObjCls, (INT32)(End - (*Ptr)));
+  if (Ret & 0x80) {
+    return FALSE;
+  }
+
+  // MU_CHANGE [END] - CodeQL change
+
   if ((ObjTag == (INT32)(Tag & CRYPTO_ASN1_TAG_VALUE_MASK)) &&
       (ObjCls == (INT32)(Tag & CRYPTO_ASN1_TAG_CLASS_MASK)))
   {