diff -r d69afa89c2ee -r bc9705db542b src/sim/syscall_emul.hh
--- a/src/sim/syscall_emul.hh	Sun Apr 29 02:26:34 2012 -0700
+++ b/src/sim/syscall_emul.hh	Sun Apr 29 02:38:56 2012 -0700
@@ -1004,6 +1004,9 @@
     int tgt_fd = p->getSyscallArg(tc, index);
     // int offset = p->getSyscallArg(tc, index);
 
+    if (length > 0x100000000ULL)
+        panic("mmap length argument %#x is unreasonably large.\n", length);
+
     if (!(flags & OS::TGT_MAP_ANONYMOUS)) {
         Process::FdMap *fd_map = p->sim_fd_obj(tgt_fd);
         if (!fd_map || fd_map->fd < 0) {