From 33ddef36177bbf9aeb09581e83b2b41438dfec2b Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Tue, 6 Apr 2021 17:24:31 +0200
Subject: [PATCH] ngtcp2+gnutls: clear credentials when freed

... to avoid double-free.

Reported-by: Kenneth Davidson
Fixes #6824
Closes #6856
---
 lib/vquic/ngtcp2.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/vquic/ngtcp2.c b/lib/vquic/ngtcp2.c
index 9569431ca2..69dd14074f 100644
--- a/lib/vquic/ngtcp2.c
+++ b/lib/vquic/ngtcp2.c
@@ -873,8 +873,10 @@ static void qs_disconnect(struct quicsocket *qs)
 #endif
   qs->ssl = NULL;
 #ifdef USE_GNUTLS
-  if(qs->cred)
+  if(qs->cred) {
     gnutls_certificate_free_credentials(qs->cred);
+    qs->cred = NULL;
+  }
 #endif
   for(i = 0; i < 3; i++)
     Curl_safefree(qs->crypto_data[i].buf);
-- 
2.47.3