Move __cleanup into mprotect'ed page to prevent unintentional modifications

similar to the atexit handlers. Idea and help deraadt@, ok deraadt@

1 files changed, 4 insertions, 6 deletions

diff --git a/src/lib/libc/stdlib/exit.c b/src/lib/libc/stdlib/exit.c
index c69639125e..e22bd5178e 100644
--- a/src/lib/libc/stdlib/exit.c
+++ b/src/lib/libc/stdlib/exit.c
@@ -32,7 +32,7 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
-static char *rcsid = "$OpenBSD: exit.c,v 1.7 2002/08/30 07:58:07 dhartmei Exp $";
+static char *rcsid = "$OpenBSD: exit.c,v 1.8 2002/09/14 22:03:14 dhartmei Exp $";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/types.h>
@@ -42,8 +42,6 @@ static char *rcsid = "$OpenBSD: exit.c,v 1.7 2002/08/30 07:58:07 dhartmei Exp $"
 #include "atexit.h"
 #include "thread_private.h"
 
-void (*__cleanup)();
-
 /*
  * This variable is zero until a process has created a thread.
  * It is used to avoid calling locking functions in libc when they
@@ -67,13 +65,13 @@ exit(status)
                 p = __atexit;
                 while (p != NULL) {
                         for (n = p->ind; --n >= 0;)
-                                (*p->fns[n])();
+                                if (p->fns[n] != NULL)
+                                        (*p->fns[n])();
                         q = p;
                         p = p->next;
                         munmap(q, pgsize);
                 }
         }
-        if (__cleanup)
-                (*__cleanup)();
+        /* cleanup, if registered, was called through fns[0] in the last page */
         _exit(status);
 }