[newlib-cygwin/cygwin-3_6-branch] Cygwin: spawn: Lock cygheap from refresh_cygheap() until child_copy()

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5af6f6f2f3b18cb825513a1e8498016af7a2fc2e

commit 5af6f6f2f3b18cb825513a1e8498016af7a2fc2e
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Sat Jul 19 23:39:12 2025 +0900

    Cygwin: spawn: Lock cygheap from refresh_cygheap() until child_copy()
    
    ...completion in child process because the cygheap should not be
    changed to avoid mismatch between child_info::cygheap_max and
    ::cygheap_max. Otherwise, child_copy() might copy cygheap being
    modified by other process.
    
    In addition, to avoid deadlock, move close_all_files() for non-
    Cygwin processes after unlocking cygheap, since close_all_files()
    calls cfree(), which attempts to lock cygheap even when it's already
    locked.
    
    Fixes: 977ad5434cc0 ("* spawn.cc (spawn_guts): Call refresh_cygheap before creating a new process to ensure that cygheap_max is up-to-date.")
    Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
    Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
    (cherry picked from commit 9b667234bfa6220dcca1afa1233a928d9100cfde)

Diff:
---
 winsup/cygwin/spawn.cc | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index cb58b6eed..7f2f5a8aa 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -542,7 +542,6 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	::cygheap->ctty ? ::cygheap->ctty->tc_getpgid () : 0;
       if (!iscygwin () && ctty_pgid && ctty_pgid != myself->pgid)
 	c_flags |= CREATE_NEW_PROCESS_GROUP;
-      refresh_cygheap ();
 
       if (mode == _P_DETACH)
 	/* all set */;
@@ -611,6 +610,8 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 
       cygpid = (mode != _P_OVERLAY) ? create_cygwin_pid () : myself->pid;
 
+      cygheap->lock ();
+      refresh_cygheap ();
       wchar_t wcmd[(size_t) cmd];
       if (!::cygheap->user.issetuid ()
 	  || (::cygheap->user.saved_uid == ::cygheap->user.real_uid
@@ -728,6 +729,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	    ::cygheap->user.reimpersonate ();
 
 	  res = -1;
+	  cygheap->unlock ();
 	  __leave;
 	}
 
@@ -764,8 +766,6 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	  NtClose (old_winpid_hdl);
 	  real_path.get_wide_win32_path (myself->progname); // FIXME: race?
 	  sigproc_printf ("new process name %W", myself->progname);
-	  if (!iscygwin ())
-	    close_all_files ();
 	}
       else
 	{
@@ -781,6 +781,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	      if (get_errno () != ENOMEM)
 		set_errno (EAGAIN);
 	      res = -1;
+	      cygheap->unlock ();
 	      __leave;
 	    }
 	  child->dwProcessId = pi.dwProcessId;
@@ -816,6 +817,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	      CloseHandle (pi.hProcess);
 	      ForceCloseHandle (pi.hThread);
 	      res = -1;
+	      cygheap->unlock ();
 	      __leave;
 	    }
 	}
@@ -844,6 +846,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	/* Just mark a non-cygwin process as 'synced'.  We will still eventually
 	   wait for it to exit in maybe_set_exit_code_from_windows(). */
 	synced = iscygwin () ? sync (pi.dwProcessId, pi.hProcess, INFINITE) : true;
+      cygheap->unlock ();
 
       switch (mode)
 	{
@@ -860,8 +863,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	    }
 	  else
 	    {
-	      if (iscygwin ())
-		close_all_files (true);
+	      close_all_files (iscygwin ());
 	      if (!my_wr_proc_pipe
 		  && WaitForSingleObject (pi.hProcess, 0) == WAIT_TIMEOUT)
 		wait_for_myself ();