wintrust: In SoftpubLoadSignature, don't assume a message is present.

dlls/wintrust/softpub.c

@@ -452,13 +452,16 @@ static BOOL WINTRUST_VerifySigner(CRYPT_PROVIDER_DATA *data, DWORD signerIdx)
 HRESULT WINAPI SoftpubLoadSignature(CRYPT_PROVIDER_DATA *data)
 {
     BOOL ret;
-    DWORD signerCount, size;
 
     TRACE("(%p)\n", data);
 
     if (!data->padwTrustStepErrors)
         return S_FALSE;
 
+    if (data->hMsg)
+    {
+        DWORD signerCount, size;
+
         size = sizeof(signerCount);
         ret = CryptMsgGetParam(data->hMsg, CMSG_SIGNER_COUNT_PARAM, 0,
          &signerCount, &size);
@@ -474,6 +477,9 @@ HRESULT WINAPI SoftpubLoadSignature(CRYPT_PROVIDER_DATA *data)
         }
         else
             SetLastError(TRUST_E_NOSIGNATURE);
+    }
+    else
+        ret = TRUE;
     if (!ret)
         data->padwTrustStepErrors[TRUSTERROR_STEP_FINAL_OBJPROV] =
          GetLastError();