glibc/fix-locking-in-_IO_cleanup.patch

Always do locking when accessing streams (bug 15142, bug 14697)

Now that abort no longer calls fflush there is no reason to avoid locking
the stdio streams anywhere.  This fixes a conformance issue and potential
heap corruption during exit.  The test nptl/tst-stdio1 is removed as that
was expecting the problematic behaviour.

Index: glibc-2.32/libio/genops.c
===================================================================
--- glibc-2.32.orig/libio/genops.c
+++ glibc-2.32/libio/genops.c
@@ -682,7 +682,7 @@ _IO_adjust_column (unsigned start, const
 libc_hidden_def (_IO_adjust_column)
 
 int
-_IO_flush_all_lockp (int do_lock)
+_IO_flush_all (void)
 {
   int result = 0;
   FILE *fp;
@@ -695,8 +695,7 @@ _IO_flush_all_lockp (int do_lock)
   for (fp = (FILE *) _IO_list_all; fp != NULL; fp = fp->_chain)
     {
       run_fp = fp;
-      if (do_lock)
-	_IO_flockfile (fp);
+      _IO_flockfile (fp);
 
       if (((fp->_mode <= 0 && fp->_IO_write_ptr > fp->_IO_write_base)
 	   || (_IO_vtable_offset (fp) == 0
@@ -706,8 +705,7 @@ _IO_flush_all_lockp (int do_lock)
 	  && _IO_OVERFLOW (fp, EOF) == EOF)
 	result = EOF;
 
-      if (do_lock)
-	_IO_funlockfile (fp);
+      _IO_funlockfile (fp);
       run_fp = NULL;
     }
 
@@ -718,14 +716,6 @@ _IO_flush_all_lockp (int do_lock)
 
   return result;
 }
-
-
-int
-_IO_flush_all (void)
-{
-  /* We want locking.  */
-  return _IO_flush_all_lockp (1);
-}
 libc_hidden_def (_IO_flush_all)
 
 void
@@ -791,6 +781,9 @@ _IO_unbuffer_all (void)
     {
       int legacy = 0;
 
+      run_fp = fp;
+      _IO_flockfile (fp);
+
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
       if (__glibc_unlikely (_IO_vtable_offset (fp) != 0))
 	legacy = 1;
@@ -800,18 +793,6 @@ _IO_unbuffer_all (void)
 	  /* Iff stream is un-orientated, it wasn't used. */
 	  && (legacy || fp->_mode != 0))
 	{
-#ifdef _IO_MTSAFE_IO
-	  int cnt;
-#define MAXTRIES 2
-	  for (cnt = 0; cnt < MAXTRIES; ++cnt)
-	    if (fp->_lock == NULL || _IO_lock_trylock (*fp->_lock) == 0)
-	      break;
-	    else
-	      /* Give the other thread time to finish up its use of the
-		 stream.  */
-	      __sched_yield ();
-#endif
-
 	  if (! legacy && ! dealloc_buffers && !(fp->_flags & _IO_USER_BUF))
 	    {
 	      fp->_flags |= _IO_USER_BUF;
@@ -825,17 +806,15 @@ _IO_unbuffer_all (void)
 
 	  if (! legacy && fp->_mode > 0)
 	    _IO_wsetb (fp, NULL, NULL, 0);
-
-#ifdef _IO_MTSAFE_IO
-	  if (cnt < MAXTRIES && fp->_lock != NULL)
-	    _IO_lock_unlock (*fp->_lock);
-#endif
 	}
 
       /* Make sure that never again the wide char functions can be
 	 used.  */
       if (! legacy)
 	fp->_mode = -1;
+
+      _IO_funlockfile (fp);
+      run_fp = NULL;
     }
 
 #ifdef _IO_MTSAFE_IO
@@ -861,9 +840,7 @@ libc_freeres_fn (buffer_free)
 int
 _IO_cleanup (void)
 {
-  /* We do *not* want locking.  Some threads might use streams but
-     that is their problem, we flush them underneath them.  */
-  int result = _IO_flush_all_lockp (0);
+  int result = _IO_flush_all ();
 
   /* We currently don't have a reliable mechanism for making sure that
      C++ static destructors are executed in the correct order.
Index: glibc-2.32/libio/libioP.h
===================================================================
--- glibc-2.32.orig/libio/libioP.h
+++ glibc-2.32/libio/libioP.h
@@ -487,7 +487,6 @@ extern int _IO_new_do_write (FILE *, con
 extern int _IO_old_do_write (FILE *, const char *, size_t);
 extern int _IO_wdo_write (FILE *, const wchar_t *, size_t);
 libc_hidden_proto (_IO_wdo_write)
-extern int _IO_flush_all_lockp (int);
 extern int _IO_flush_all (void);
 libc_hidden_proto (_IO_flush_all)
 extern int _IO_cleanup (void);
Index: glibc-2.32/sysdeps/pthread/Makefile
===================================================================
--- glibc-2.32.orig/sysdeps/pthread/Makefile
+++ glibc-2.32/sysdeps/pthread/Makefile
@@ -99,7 +99,7 @@ tests += tst-cnd-basic tst-mtx-trylock t
 	 tst-signal4 tst-signal5 tst-signal6 tst-signal8 \
 	 tst-spin1 tst-spin2 tst-spin3 tst-spin4 \
 	 tst-stack1 \
-	 tst-stdio1 tst-stdio2 \
+	 tst-stdio2 \
 	 tst-pt-sysconf \
 	 tst-pt-tls1 tst-pt-tls2 \
 	 tst-tsd1 tst-tsd2 tst-tsd5 tst-tsd6 \
Index: glibc-2.32/sysdeps/pthread/tst-stdio1.c
===================================================================
--- glibc-2.32.orig/sysdeps/pthread/tst-stdio1.c
+++ /dev/null
@@ -1,55 +0,0 @@
-/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <pthread.h>
-#include <signal.h>
-#include <stdio.h>
-#include <unistd.h>
-
-static int do_test (void);
-
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
-
-static void *tf (void *a)
-{
-  flockfile (stdout);
-  /* This call should never return.  */
-  return a;
-}
-
-
-int
-do_test (void)
-{
-  pthread_t th;
-
-  flockfile (stdout);
-
-  if (pthread_create (&th, NULL, tf, NULL) != 0)
-    {
-      write_message ("create failed\n");
-      _exit (1);
-    }
-
-  delayed_exit (1);
-  xpthread_join (th);
-
-  puts ("join returned");
-
-  return 1;
-}