[edk2-devel] [PATCH v7 04/12] CryptoPkg: Fix conditionally uninitialized variable

[Michael Kubacki]

From: Michael Kubacki <michael.kubacki at 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 at microsoft.com>
Cc: Guomin Jiang <guomin.jiang at intel.com>
Cc: Jian J Wang <jian.j.wang at intel.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Michael Kubacki <mikuback at linux.microsoft.com>
Cc: Xiaoyu Lu <xiaoyu1.lu at intel.com>
Co-authored-by: Erich McMillan <emcmillan at microsoft.com>
Signed-off-by: Michael Kubacki <michael.kubacki at microsoft.com>
Reviewed-by: Jiewen Yao <Jiewen.yao at intel.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..1182323b63ee 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) == 0x00) && (Asn1Tag != V_ASN1_SEQUENCE)) {
     return FALSE;
   }
 
@@ -848,7 +849,7 @@ X509GetTBSCert (
   //
   // Verify the parsed TBSCertificate is one correct SEQUENCE data.
   //
-  if (Asn1Tag != V_ASN1_SEQUENCE) {
+  if (((Inf & 0x80) == 0x00) && (Asn1Tag != V_ASN1_SEQUENCE)) {
     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) == 0x00) &&
+      (ObjTag == (INT32)(Tag & CRYPTO_ASN1_TAG_VALUE_MASK)) &&
       (ObjCls == (INT32)(Tag & CRYPTO_ASN1_TAG_CLASS_MASK)))
   {
     *Length = (UINTN)ObjLength;
-- 
2.40.0.windows.1



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