From 729cb70bcf232a1da956ec3725c1f76e28b3caa5 Mon Sep 17 00:00:00 2001
From: Corinna Vinschen <corinna@vinschen.de>
Date: Fri, 28 Feb 2020 13:21:05 +0100
Subject: [PATCH] Cygwin: AF_UNIX: rework fixup_after_exec

fhandler_socket_unix::fixup_after_exec incorrectly calls
fhandler_socket_unix::fixup_after_fork with a NULL parent process
handle.  Not only that calling DuplicateHandle with a NULL parent
handle fails, but it's utterly wrong trying to duplicate the handles
at all here.

Rather just set some important values to NULL and reopen the shared
memory region.  Create a fixup_helper method to call common code from
fixup_after_fork and fixup_after_exec.

Add comments to other invocations of fixup_after_fork with NULL
handle to mark them as correct this way.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
---
 winsup/cygwin/fhandler.h              |  1 +
 winsup/cygwin/fhandler_socket_inet.cc |  2 +-
 winsup/cygwin/fhandler_socket_unix.cc | 21 +++++++++++++--------
 winsup/cygwin/fhandler_tty.cc         |  2 +-
 4 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 55f18aebd..90805abb8 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1076,6 +1076,7 @@ class fhandler_socket_unix : public fhandler_socket
   void fixup_after_fork (HANDLE parent);
   void fixup_after_exec ();
   void set_close_on_exec (bool val);
+  void fixup_helper ();
 
  public:
   fhandler_socket_unix ();
diff --git a/winsup/cygwin/fhandler_socket_inet.cc b/winsup/cygwin/fhandler_socket_inet.cc
index 6f4383861..703781d17 100644
--- a/winsup/cygwin/fhandler_socket_inet.cc
+++ b/winsup/cygwin/fhandler_socket_inet.cc
@@ -534,7 +534,7 @@ void
 fhandler_socket_wsock::fixup_after_exec ()
 {
   if (need_fixup_before () && !close_on_exec ())
-    fixup_after_fork (NULL);
+    fixup_after_fork (NULL);	/* No parent handle required. */
 }
 
 int
diff --git a/winsup/cygwin/fhandler_socket_unix.cc b/winsup/cygwin/fhandler_socket_unix.cc
index 760f210bf..d7bb1090e 100644
--- a/winsup/cygwin/fhandler_socket_unix.cc
+++ b/winsup/cygwin/fhandler_socket_unix.cc
@@ -1149,6 +1149,16 @@ fhandler_socket_unix::set_cred ()
   scred->gid = myself->gid;
 }
 
+void
+fhandler_socket_unix::fixup_helper ()
+{
+  if (shmem_handle)
+    reopen_shmem ();
+  connect_wait_thr = NULL;
+  cwt_termination_evt = NULL;
+  cwt_param = NULL;
+}
+
 /* ========================== public methods ========================= */
 
 void
@@ -1158,20 +1168,15 @@ fhandler_socket_unix::fixup_after_fork (HANDLE parent)
   if (backing_file_handle && backing_file_handle != INVALID_HANDLE_VALUE)
     fork_fixup (parent, backing_file_handle, "backing_file_handle");
   if (shmem_handle)
-    {
-      fork_fixup (parent, shmem_handle, "shmem_handle");
-      reopen_shmem ();
-    }
-  connect_wait_thr = NULL;
-  cwt_termination_evt = NULL;
-  cwt_param = NULL;
+    fork_fixup (parent, shmem_handle, "shmem_handle");
+  fixup_helper ();
 }
 
 void
 fhandler_socket_unix::fixup_after_exec ()
 {
   if (!close_on_exec ())
-    fixup_after_fork (NULL);
+    fixup_helper ();
 }
 
 void
diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 153bdad79..b42e0aeb6 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -2974,7 +2974,7 @@ fhandler_pty_slave::fixup_after_exec ()
   reset_switch_to_pcon ();
 
   if (!close_on_exec ())
-    fixup_after_fork (NULL);
+    fixup_after_fork (NULL);	/* No parent handle required. */
   else if (get_pseudo_console ())
     {
       int used = 0;