url: cleanup dangling DOH request headers too

Follow-up to 9bc44ff64d9081

Credit to OSS-Fuzz
Bug: https://crbug.com/oss-fuzz/17269

Closes #4372

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/url.c b/lib/url.c
index 94dc9b8b2..572cd9c68 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -404,6 +404,7 @@ CURLcode Curl_close(struct Curl_easy *data)
   Curl_close(data->req.doh.probe[1].easy);
   free(data->req.doh.probe[0].serverdoh.memory);
   free(data->req.doh.probe[1].serverdoh.memory);
+  curl_slist_free_all(data->req.doh.headers);
 
   /* destruct wildcard structures if it is needed */
   Curl_wildcard_dtor(&data->wildcard);