wintrust: Add parameter check in WTHelperGetProvCertFromChain

dlls/wintrust/tests/softpub.c

@@ -1312,6 +1312,14 @@ static void test_get_known_usages(void)
      "expected ERROR_INVALID_PARAMETER, got %ld\n", GetLastError());
 }
 
+static void test_WTHelperGetProvCertFromChain(void)
+{
+    CRYPT_PROVIDER_CERT *cert;
+
+    cert = WTHelperGetProvCertFromChain(NULL, 0);
+    ok(!cert, "got certificate\n");
+}
+
 START_TEST(softpub)
 {
     InitFunctionPtrs();
@@ -1320,4 +1328,5 @@ START_TEST(softpub)
     test_wintrust();
     test_wintrust_digest();
     test_get_known_usages();
+    test_WTHelperGetProvCertFromChain();
 }

dlls/wintrust/wintrust_main.c

@@ -782,7 +782,7 @@ CRYPT_PROVIDER_CERT * WINAPI WTHelperGetProvCertFromChain(
 
     TRACE("(%p %ld)\n", pSgnr, idxCert);
 
-    if (idxCert >= pSgnr->csCertChain || !pSgnr->pasCertChain)
+    if (!pSgnr || idxCert >= pSgnr->csCertChain || !pSgnr->pasCertChain)
         return NULL;
     cert = &pSgnr->pasCertChain[idxCert];
     TRACE("returning %p\n", cert);