multi: shut down CONNECT in Curl_detach_connnection

... to prevent a lingering pointer that would lead to a double-free.

Added test 1939 to verify.

Reported-by: Stephen M. Coakley
Fixes #7982
Closes #7986

6 files changed, 138 insertions, 7 deletions

diff --git a/lib/http_proxy.c b/lib/http_proxy.c
index fc050a07d..cfe616fa6 100644
--- a/lib/http_proxy.c
+++ b/lib/http_proxy.c
@@ -198,11 +198,11 @@ static CURLcode connect_init(struct Curl_easy *data, bool reinit)
   return CURLE_OK;
 }
 
-static void connect_done(struct Curl_easy *data)
+void Curl_connect_done(struct Curl_easy *data)
 {
   struct connectdata *conn = data->conn;
   struct http_connect_state *s = conn->connect_state;
-  if(s->tunnel_state != TUNNEL_EXIT) {
+  if(s && (s->tunnel_state != TUNNEL_EXIT)) {
     s->tunnel_state = TUNNEL_EXIT;
     Curl_dyn_free(&s->rcvbuf);
     Curl_dyn_free(&s->req);
@@ -662,7 +662,7 @@ static CURLcode CONNECT(struct Curl_easy *data,
     if(s->close_connection && data->req.newurl) {
       conn->bits.proxy_connect_closed = TRUE;
       infof(data, "Connect me again please");
-      connect_done(data);
+      Curl_connect_done(data);
     }
     else {
       free(data->req.newurl);
@@ -974,7 +974,7 @@ static CURLcode CONNECT(struct Curl_easy *data,
       if(conn->bits.close && data->req.newurl) {
         conn->bits.proxy_connect_closed = TRUE;
         infof(data, "Connect me again please");
-        connect_done(data);
+        Curl_connect_done(data);
       }
       else {
         free(data->req.newurl);
@@ -1048,7 +1048,7 @@ CURLcode Curl_proxyCONNECT(struct Curl_easy *data,
   result = CONNECT(data, sockindex, hostname, remote_port);
 
   if(result || Curl_connect_complete(conn))
-    connect_done(data);
+    Curl_connect_done(data);
 
   return result;
 }
diff --git a/lib/multi.c b/lib/multi.c
index f307d63b9..ce634fcac 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -878,6 +878,7 @@ void Curl_detach_connnection(struct Curl_easy *data)
 {
   struct connectdata *conn = data->conn;
   if(conn) {
+    Curl_connect_done(data); /* if mid-CONNECT, shut it down */
     Curl_llist_remove(&conn->easyq, &data->conn_queue, NULL);
     Curl_ssl_detach_conn(data, conn);
   }
diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
index 9a8b64bed..b6a503e72 100644
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -216,7 +216,7 @@ test1800 test1801 \
 test1908 test1909 test1910 test1911 test1912 test1913 test1914 test1915 \
 test1916 test1917 test1918 \
 \
-test1933 test1934 test1935 test1936 test1937 test1938 \
+test1933 test1934 test1935 test1936 test1937 test1938 test1939 \
 \
 test2000 test2001 test2002 test2003 test2004 \
 \
diff --git a/tests/data/test1939 b/tests/data/test1939
new file mode 100644
index 000000000..0b9987b5b
--- /dev/null
+++ b/tests/data/test1939
@@ -0,0 +1,52 @@
+<testcase>
+<info>
+<keywords>
+CONNECT
+curl_easy_cleanup
+</keywords>
+</info>
+
+# Server-side
+<reply>
+<data nocheck="yes">
+HTTP/1.1 302 OK
+Date: Thu, 09 Nov 2010 14:49:00 GMT
+Server: test-server/fake
+Content-Type: text/html
+Content-Length: 0
+Location: /%TESTNUMBER0002
+
+</data>
+<data2>
+HTTP/1.1 200 OK
+Date: Thu, 09 Nov 2010 14:49:00 GMT
+Server: test-server/fake
+Content-Type: text/html
+Content-Length: 0
+
+</data2>
+</reply>
+
+# Client-side
+<client>
+<server>
+https
+http-proxy
+</server>
+
+<name>
+curl_easy_cleanup without curl_multi_remove_handle - in CONNECT
+</name>
+<tool>
+lib%TESTNUMBER
+</tool>
+
+<command>
+https://%HOSTIP:%HTTPPORT/%TESTNUMBER http://%HOSTIP:%PROXYPORT
+</command>
+</client>
+
+# Verify data after the test has been "shot"
+<verify>
+</verify>
+</testcase>
diff --git a/tests/libtest/Makefile.inc b/tests/libtest/Makefile.inc
index 8cea7c014..62a7675b1 100644
--- a/tests/libtest/Makefile.inc
+++ b/tests/libtest/Makefile.inc
@@ -61,7 +61,8 @@ noinst_PROGRAMS = chkhostname libauthretry libntlmconnect                \
  lib1591 lib1592 lib1593 lib1594 lib1596 \
          lib1905 lib1906 lib1907 lib1908 lib1910 lib1911 lib1912 lib1913 \
          lib1915 lib1916 lib1917 lib1918 lib1933 lib1934 lib1935 lib1936 \
- lib1937 lib1938 lib3010
+ lib1937 lib1938 lib1939 \
+ lib3010
 
 chkdecimalpoint_SOURCES = chkdecimalpoint.c ../../lib/mprintf.c \
  ../../lib/curl_ctype.c  ../../lib/dynbuf.c ../../lib/strdup.c
@@ -715,6 +716,10 @@ lib1938_SOURCES = lib1938.c $(SUPPORTFILES)
 lib1938_LDADD = $(TESTUTIL_LIBS)
 lib1938_CPPFLAGS = $(AM_CPPFLAGS)
 
+lib1939_SOURCES = lib1939.c $(SUPPORTFILES)
+lib1939_LDADD = $(TESTUTIL_LIBS)
+lib1939_CPPFLAGS = $(AM_CPPFLAGS)
+
 lib3010_SOURCES = lib3010.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 lib3010_LDADD = $(TESTUTIL_LIBS)
 lib3010_CPPFLAGS = $(AM_CPPFLAGS)
diff --git a/tests/libtest/lib1939.c b/tests/libtest/lib1939.c
new file mode 100644
index 000000000..644617712
--- /dev/null
+++ b/tests/libtest/lib1939.c
@@ -0,0 +1,73 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "test.h"
+
+#include "memdebug.h"
+
+int test(char *URL)
+{
+  CURLM *multi;
+  CURL *easy;
+  int running_handles;
+
+  curl_global_init(CURL_GLOBAL_DEFAULT);
+
+  multi = curl_multi_init();
+  if(!multi)
+    return 1;
+
+  easy = curl_easy_init();
+  if(easy) {
+    CURLcode c;
+    CURLMcode m;
+
+    /* Crash only happens when using HTTPS */
+    c = curl_easy_setopt(easy, CURLOPT_URL, URL);
+    if(!c)
+      /* Any old HTTP tunneling proxy will do here */
+      c = curl_easy_setopt(easy, CURLOPT_PROXY, libtest_arg2);
+
+    if(c)
+      return 2;
+
+    /* We're going to drive the transfer using multi interface here, because we
+       want to stop during the middle. */
+    m = curl_multi_add_handle(multi, easy);
+
+    if(!m)
+      /* Run the multi handle once, just enough to start establishing an HTTPS
+         connection. */
+      m = curl_multi_perform(multi, &running_handles);
+
+    if(m)
+      return 3;
+
+    /* Close the easy handle *before* the multi handle. Doing it the other way
+       around avoids the issue. */
+    curl_easy_cleanup(easy);
+  }
+  curl_multi_cleanup(multi); /* double-free happens here */
+
+  curl_global_cleanup();
+  return CURLE_OK;
+}