[newlib-cygwin/cygwin-3_5-branch] Cygwin: console: Fix exit code for non-cygwin process.

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=aa73e115242612bf8b5f8670c0c7d398693d1d84

commit aa73e115242612bf8b5f8670c0c7d398693d1d84
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Fri Feb 2 13:59:19 2024 +0900

    Cygwin: console: Fix exit code for non-cygwin process.
    
    If non-cygwin process is executed in console, the exit code is not
    set correctly. This is because the stub process for non-cygwin app
    crashes in fhandler_console::set_disable_master_thread() due to NULL
    pointer dereference. This bug was introduced by the commit:
    3721a756b0d8 ("Cygwin: console: Make the console accessible from
    other terminals."), that the pointer cons is accessed before fixing
    when it is NULL. This patch fixes the issue.
    
    Fixes: 3721a756b0d8 ("Cygwin: console: Make the console accessible from other terminals.")
    Reported-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
    Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

Diff:
---
 winsup/cygwin/fhandler/console.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/winsup/cygwin/fhandler/console.cc b/winsup/cygwin/fhandler/console.cc
index b924a6bf3..6a42b4949 100644
--- a/winsup/cygwin/fhandler/console.cc
+++ b/winsup/cygwin/fhandler/console.cc
@@ -4537,9 +4537,6 @@ fhandler_console::need_console_handler ()
 void
 fhandler_console::set_disable_master_thread (bool x, fhandler_console *cons)
 {
-  const _minor_t unit = cons->get_minor ();
-  if (con.disable_master_thread == x)
-    return;
   if (cons == NULL)
     {
       if (cygheap->ctty && cygheap->ctty->get_major () == DEV_CONS_MAJOR)
@@ -4547,6 +4544,9 @@ fhandler_console::set_disable_master_thread (bool x, fhandler_console *cons)
       else
 	return;
     }
+  const _minor_t unit = cons->get_minor ();
+  if (con.disable_master_thread == x)
+    return;
   cons->acquire_input_mutex (mutex_timeout);
   con.disable_master_thread = x;
   cons->release_input_mutex ();