From 088398af06f26d8df0d008f8cfb1cda422a4a4fc Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Wed, 25 Jun 2025 10:25:53 +0200
Subject: [PATCH] make socks asserts on hostname and port earlier to catch
 where fuzzer crashes

---
 lib/connect.c | 4 ++++
 lib/socks.c   | 7 +++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/connect.c b/lib/connect.c
index 07e334ff2a..f41403c316 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -1297,6 +1297,8 @@ connect_sub_chain:
   if(ctx->state < CF_SETUP_CNNCT_SOCKS && cf->conn->bits.socksproxy) {
     /* Where do we need the SOCKS to connect to? */
     if(cf->conn->bits.httpproxy) {
+      DEBUGASSERT(cf->conn->http_proxy.host.name);
+      DEBUGASSERT(cf->conn->http_proxy.port > 0);
       result = Curl_cf_socks_proxy_insert_after(
         cf, data, cf->conn->socks_proxy.proxytype, "HTTP proxy",
         cf->conn->http_proxy.host.name, (int)cf->conn->http_proxy.port,
@@ -1313,6 +1315,8 @@ connect_sub_chain:
         cf->conn->bits.conn_to_port ? cf->conn->conn_to_port :
         cf->conn->remote_port;
 
+      DEBUGASSERT(sx_hostname);
+      DEBUGASSERT(sx_remote_port > 0);
       result = Curl_cf_socks_proxy_insert_after(
         cf, data, cf->conn->socks_proxy.proxytype, NULL,
         sx_hostname, sx_remote_port,
diff --git a/lib/socks.c b/lib/socks.c
index 08286271c3..092f9341bf 100644
--- a/lib/socks.c
+++ b/lib/socks.c
@@ -1105,8 +1105,6 @@ static CURLcode socks_proxy_cf_connect(struct Curl_cfilter *cf,
      * but ignore the "connect to port" (use the secondary port)
      */
     sxstate(sx, data, CONNECT_SOCKS_INIT);
-    DEBUGASSERT(sx->hostname);
-    DEBUGASSERT(sx->remote_port > 0);
   }
 
   result = connect_SOCKS(cf, sx, data);
@@ -1223,16 +1221,17 @@ CURLcode Curl_cf_socks_proxy_insert_after(struct Curl_cfilter *cf_at,
   if(!sx)
     return CURLE_OUT_OF_MEMORY;
 
-  result = Curl_cf_create(&cf, &Curl_cft_socks_proxy, NULL);
+  result = Curl_cf_create(&cf, &Curl_cft_socks_proxy, sx);
   if(!result) {
     Curl_conn_cf_insert_after(cf_at, cf);
     sx->proxy_type = proxy_type;
     sx->remote_type = remote_type;
     sx->hostname = remote_host;
     sx->remote_port = remote_port;
+    DEBUGASSERT(sx->hostname);
+    DEBUGASSERT(sx->remote_port > 0);
     sx->proxy_user = proxy_user;
     sx->proxy_password = proxy_password;
-    cf->ctx = sx;
     sx = NULL;
   }
   free(sx);