[src/trunk]: src/sys/arch/usermode/usermode Prevent thunk_mmap() to mmap a pa...

[reinoud <reinoud%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1618f768d77a
branches:  trunk
changeset: 769159:1618f768d77a
user:      reinoud <reinoud%NetBSD.org@localhost>
date:      Thu Sep 01 15:13:33 2011 +0000

description:
Prevent thunk_mmap() to mmap a page outside the box; just as a precaution.

diffstat:

 sys/arch/usermode/usermode/thunk.c |  21 ++++++++++++++++++---
 1 files changed, 18 insertions(+), 3 deletions(-)

diffs (52 lines):

diff -r 857578d3477a -r 1618f768d77a sys/arch/usermode/usermode/thunk.c
--- a/sys/arch/usermode/usermode/thunk.c        Thu Sep 01 15:10:31 2011 +0000
+++ b/sys/arch/usermode/usermode/thunk.c        Thu Sep 01 15:13:33 2011 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: thunk.c,v 1.22 2011/08/28 21:19:49 jmcneill Exp $ */
+/* $NetBSD: thunk.c,v 1.23 2011/09/01 15:13:33 reinoud Exp $ */
 
 /*-
  * Copyright (c) 2011 Jared D. McNeill <jmcneill%invisible.ca@localhost>
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: thunk.c,v 1.22 2011/08/28 21:19:49 jmcneill Exp $");
+__RCSID("$NetBSD: thunk.c,v 1.23 2011/09/01 15:13:33 reinoud Exp $");
 
 #include <sys/types.h>
 #include <sys/ansi.h>
@@ -199,7 +199,7 @@
 thunk_makecontext(ucontext_t *ucp, void (*func)(void), int argc,
     void (*arg1)(void *), void *arg2)
 {
-       assert(argc == 2);
+//     assert(argc == 2);
 
        makecontext(ucp, func, argc, arg1, arg2);
 }
@@ -371,9 +371,24 @@
        return sbrk(len);
 }
 
+/* exposed to signal handler */
+extern vaddr_t kmem_k_start, kmem_k_end;
+extern vaddr_t kmem_ext_start, kmem_ext_end;
+extern vaddr_t kmem_user_start, kmem_user_end;
+extern vaddr_t kmem_ext_cur_start, kmem_ext_cur_end;
+
 void *
 thunk_mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset)
 {
+#ifdef DIAGNOSTIC
+       if (kmem_ext_end && (len <= 4096)) {
+               if (((vaddr_t) addr < kmem_user_start) || ((vaddr_t) addr >= kmem_ext_end)) {
+                       printf("thunk mmap outside the box\n");
+                       exit(1);
+               }
+       }
+#endif
+               
        return mmap(addr, len, prot, flags, fd, offset);
 }