vtls: avoid NULL deref on bad PEM input

Spotted by Coverity

Closes #17274

diff --git a/lib/vtls/vtls.c b/lib/vtls/vtls.c
index fa2b0fe92b5799ff970a08202fbcaa82f303d6a0..3b335e28718c8d8eacd71bb9da2100cd3ab44000 100644 (file)
--- a/lib/vtls/vtls.c
+++ b/lib/vtls/vtls.c
@@ -698,9 +698,12 @@ static CURLcode pubkey_pem_to_der(const char *pem,
     ++pem_count;
   }
 
-  result = curlx_base64_decode(curlx_dyn_ptr(&pbuf), der, der_len);
-
-  curlx_dyn_free(&pbuf);
+  if(curlx_dyn_len(&pbuf)) {
+    result = curlx_base64_decode(curlx_dyn_ptr(&pbuf), der, der_len);
+    curlx_dyn_free(&pbuf);
+  }
+  else
+    result = CURLE_BAD_CONTENT_ENCODING;
 
   return result;
 }