diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 62682f357..08339465c 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,11 @@
+2004-02-25  Brian Ford <ford@vss.fsi.com>,
+	    Corinna Vinschen  <corinna@vinschen.de>
+
+	* miscfuncs.cc (check_invalid_virtual_addr): New function.
+	* winsup.h (check_invalid_virtual_addr): Declare.
+	* mmap.cc (munmap): Call check_invalid_virtual_addr instead of
+	IsBadReadPtr.
+
 2004-02-24  Christopher Faylor  <cgf@redhat.com>
 
 	* gendef (stabilize_sig_stack): Correctly align this pointer for call
diff --git a/winsup/cygwin/miscfuncs.cc b/winsup/cygwin/miscfuncs.cc
index 4207c4d1a..7947365f4 100644
--- a/winsup/cygwin/miscfuncs.cc
+++ b/winsup/cygwin/miscfuncs.cc
@@ -214,6 +214,18 @@ __check_invalid_read_ptr_errno (const void *s, unsigned sz)
   return set_errno (EFAULT);
 }
 
+int __stdcall
+check_invalid_virtual_addr (const void *s, unsigned sz)
+{
+  MEMORY_BASIC_INFORMATION mbuf;
+  void *end;
+
+  for (end = (char *) s + sz; s < end; s = (char *) s + mbuf.RegionSize)
+    if (!VirtualQuery (s, &mbuf, sizeof mbuf))
+      return EINVAL;
+  return 0;
+}
+
 ssize_t
 check_iovec_for_read (const struct iovec *iov, int iovcnt)
 {
diff --git a/winsup/cygwin/mmap.cc b/winsup/cygwin/mmap.cc
index 4f8ea6e14..cacefea41 100644
--- a/winsup/cygwin/mmap.cc
+++ b/winsup/cygwin/mmap.cc
@@ -641,7 +641,7 @@ munmap (void *addr, size_t len)
 
   /* Error conditions according to SUSv3 */
   if (!addr || ((DWORD)addr % getpagesize ()) || !len
-      || IsBadReadPtr (addr, len))
+      || check_invalid_virtual_addr (addr, len))
     {
       set_errno (EINVAL);
       syscall_printf ("-1 = munmap(): Invalid parameters");
diff --git a/winsup/cygwin/winsup.h b/winsup/cygwin/winsup.h
index 93cdceed2..a7e38d772 100644
--- a/winsup/cygwin/winsup.h
+++ b/winsup/cygwin/winsup.h
@@ -276,6 +276,7 @@ int __stdcall __check_null_invalid_struct (void *s, unsigned sz) __attribute__ (
 int __stdcall __check_null_invalid_struct_errno (void *s, unsigned sz) __attribute__ ((regparm(2)));
 int __stdcall __check_invalid_read_ptr (const void *s, unsigned sz) __attribute__ ((regparm(2)));
 int __stdcall __check_invalid_read_ptr_errno (const void *s, unsigned sz) __attribute__ ((regparm(2)));
+int __stdcall check_invalid_virtual_addr (const void *s, unsigned sz) __attribute__ ((regparm(2)));
 
 #define check_null_invalid_struct(s) \
   __check_null_invalid_struct ((s), sizeof (*(s)))