Avoid make_readable ( NULL, ... ) in ioctl SIOCGIFCONF.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@324

diff --git a/vg_syscall_mem.c b/vg_syscall_mem.c
index bb7c84cac48faeb13acca83ed8d64c0807fcdf78..0c5d88861e4febb8d0da8fc42cd620792fa4bcba 100644 (file)
--- a/vg_syscall_mem.c
+++ b/vg_syscall_mem.c
@@ -1792,7 +1792,9 @@ void VG_(perform_assumed_nonblocking_syscall) ( ThreadId tid )
                KERNEL_DO_SYSCALL(tid,res);
                if (!VG_(is_kerror)(res) && res == 0 && arg3 ) {
                   struct ifconf *ifc = (struct ifconf *) arg3;
-                  make_readable ( (Addr)(ifc->ifc_buf), (UInt)(ifc->ifc_len) );
+                  if (ifc->ifc_buf != NULL)
+                     make_readable ( (Addr)(ifc->ifc_buf), 
+                                     (UInt)(ifc->ifc_len) );
                }
                break;
             case SIOCGSTAMP: