crypt32: Separate checking the tag of encoded bits from decoding the bits.

dlls/crypt32/decode.c

@@ -96,6 +96,7 @@ static BOOL CRYPT_AsnDecodeBool(const BYTE *pbEncoded, DWORD cbEncoded,
 static BOOL CRYPT_AsnDecodeOctetsInternal(const BYTE *pbEncoded,
  DWORD cbEncoded, DWORD dwFlags, void *pvStructInfo, DWORD *pcbStructInfo,
  DWORD *pcbDecoded);
+/* Doesn't check the tag, assumes the caller does so */
 static BOOL CRYPT_AsnDecodeBitsInternal(const BYTE *pbEncoded, DWORD cbEncoded,
  DWORD dwFlags, void *pvStructInfo, DWORD *pcbStructInfo, DWORD *pcbDecoded);
 static BOOL CRYPT_AsnDecodeIntInternal(const BYTE *pbEncoded, DWORD cbEncoded,
@@ -3298,64 +3299,54 @@ static BOOL CRYPT_AsnDecodeBitsInternal(const BYTE *pbEncoded, DWORD cbEncoded,
  DWORD dwFlags, void *pvStructInfo, DWORD *pcbStructInfo, DWORD *pcbDecoded)
 {
     BOOL ret;
+    DWORD bytesNeeded, dataLen;
+    BYTE lenBytes = GET_LEN_BYTES(pbEncoded[1]);
 
     TRACE("(%p, %d, 0x%08x, %p, %d, %p)\n", pbEncoded, cbEncoded, dwFlags,
      pvStructInfo, *pcbStructInfo, pcbDecoded);
 
-    if (pbEncoded[0] == ASN_BITSTRING)
+    if ((ret = CRYPT_GetLen(pbEncoded, cbEncoded, &dataLen)))
     {
-        DWORD bytesNeeded, dataLen;
-        BYTE lenBytes = GET_LEN_BYTES(pbEncoded[1]);
-
-        if ((ret = CRYPT_GetLen(pbEncoded, cbEncoded, &dataLen)))
+        if (dwFlags & CRYPT_DECODE_NOCOPY_FLAG)
+            bytesNeeded = sizeof(CRYPT_BIT_BLOB);
+        else
+            bytesNeeded = dataLen - 1 + sizeof(CRYPT_BIT_BLOB);
+        if (pcbDecoded)
+            *pcbDecoded = 1 + lenBytes + dataLen;
+        if (!pvStructInfo)
+            *pcbStructInfo = bytesNeeded;
+        else if (*pcbStructInfo < bytesNeeded)
+        {
+            *pcbStructInfo = bytesNeeded;
+            SetLastError(ERROR_MORE_DATA);
+            ret = FALSE;
+        }
+        else
         {
+            CRYPT_BIT_BLOB *blob;
+
+            *pcbStructInfo = bytesNeeded;
+            blob = (CRYPT_BIT_BLOB *)pvStructInfo;
+            blob->cbData = dataLen - 1;
+            blob->cUnusedBits = *(pbEncoded + 1 + lenBytes);
             if (dwFlags & CRYPT_DECODE_NOCOPY_FLAG)
-                bytesNeeded = sizeof(CRYPT_BIT_BLOB);
-            else
-                bytesNeeded = dataLen - 1 + sizeof(CRYPT_BIT_BLOB);
-            if (pcbDecoded)
-                *pcbDecoded = 1 + lenBytes + dataLen;
-            if (!pvStructInfo)
-                *pcbStructInfo = bytesNeeded;
-            else if (*pcbStructInfo < bytesNeeded)
             {
-                *pcbStructInfo = bytesNeeded;
-                SetLastError(ERROR_MORE_DATA);
-                ret = FALSE;
+                blob->pbData = (BYTE *)pbEncoded + 2 + lenBytes;
             }
             else
             {
-                CRYPT_BIT_BLOB *blob;
-
-                *pcbStructInfo = bytesNeeded;
-                blob = (CRYPT_BIT_BLOB *)pvStructInfo;
-                blob->cbData = dataLen - 1;
-                blob->cUnusedBits = *(pbEncoded + 1 + lenBytes);
-                if (dwFlags & CRYPT_DECODE_NOCOPY_FLAG)
-                {
-                    blob->pbData = (BYTE *)pbEncoded + 2 + lenBytes;
-                }
-                else
+                assert(blob->pbData);
+                if (blob->cbData)
                 {
-                    assert(blob->pbData);
-                    if (blob->cbData)
-                    {
-                        BYTE mask = 0xff << blob->cUnusedBits;
+                    BYTE mask = 0xff << blob->cUnusedBits;
 
-                        memcpy(blob->pbData, pbEncoded + 2 + lenBytes,
-                         blob->cbData);
-                        blob->pbData[blob->cbData - 1] &= mask;
-                    }
+                    memcpy(blob->pbData, pbEncoded + 2 + lenBytes,
+                     blob->cbData);
+                    blob->pbData[blob->cbData - 1] &= mask;
                 }
             }
         }
     }
-    else
-    {
-        SetLastError(CRYPT_E_ASN1_BADTAG);
-        ret = FALSE;
-    }
-    TRACE("returning %d (%08x)\n", ret, GetLastError());
     return ret;
 }
 
@@ -3372,7 +3363,17 @@ static BOOL WINAPI CRYPT_AsnDecodeBits(DWORD dwCertEncodingType,
     {
         DWORD bytesNeeded;
 
-        if ((ret = CRYPT_AsnDecodeBitsInternal(pbEncoded, cbEncoded,
+        if (!cbEncoded)
+        {
+            SetLastError(CRYPT_E_ASN1_CORRUPT);
+            ret = FALSE;
+        }
+        else if (pbEncoded[0] != ASN_BITSTRING)
+        {
+            SetLastError(CRYPT_E_ASN1_BADTAG);
+            ret = FALSE;
+        }
+        else if ((ret = CRYPT_AsnDecodeBitsInternal(pbEncoded, cbEncoded,
          dwFlags & ~CRYPT_DECODE_ALLOC_FLAG, NULL, &bytesNeeded, NULL)))
         {
             if (!pvStructInfo)

dlls/crypt32/tests/encode.c

@@ -3323,7 +3323,6 @@ static void test_decodeCRLDistPoints(DWORD dwEncoding)
     ret = pCryptDecodeObjectEx(dwEncoding, X509_CRL_DIST_POINTS,
      distPointWithReason, distPointWithReason[1] + 2, CRYPT_DECODE_ALLOC_FLAG,
      NULL, (BYTE *)&buf, &size);
-    todo_wine
     ok(ret, "CryptDecodeObjectEx failed: %08x\n", GetLastError());
     if (ret)
     {