ioctl(generic): don't do make_readable(NULL, ...)

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@365

diff --git a/vg_syscall_mem.c b/vg_syscall_mem.c
index 64e44df36bd25482aaf3e93b9e88567f8ad8b154..0e8ad1d1b1c102912c8fe8054b53be3fd15c20b8 100644 (file)
--- a/vg_syscall_mem.c
+++ b/vg_syscall_mem.c
@@ -2048,7 +2048,8 @@ void VG_(perform_assumed_nonblocking_syscall) ( ThreadId tid )
                }
                KERNEL_DO_SYSCALL(tid,res);
                if (size > 0 && (dir & _IOC_READ)
-                   && !VG_(is_kerror)(res) && res == 0)
+                   && !VG_(is_kerror)(res) && res == 0
+                   && arg3 != (Addr)NULL)
                   make_readable (arg3, size);
                break;
             }