randstruct: Check member structs in is_pure_ops_struct()

commit 60f2c82ed20bde57c362e66f796cf9e0e38a6dbb upstream.

While no uses in the kernel triggered this case, it was possible to have
a false negative where a struct contains other structs which contain only
function pointers because of unreachable code in is_pure_ops_struct().

Signed-off-by: Joonwon Kang <kjw1627@gmail.com>
Link: https://lore.kernel.org/r/20190727155841.GA13586@host
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
index 6d5bbd3..bd29e4e 100644 (file)
--- a/scripts/gcc-plugins/randomize_layout_plugin.c
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -443,13 +443,13 @@ static int is_pure_ops_struct(const_tree node)
                if (node == fieldtype)
                        continue;
 
-               if (!is_fptr(fieldtype))
-                       return 0;
-
-               if (code != RECORD_TYPE && code != UNION_TYPE)
+               if (code == RECORD_TYPE || code == UNION_TYPE) {
+                       if (!is_pure_ops_struct(fieldtype))
+                               return 0;
                        continue;
+               }
 
-               if (!is_pure_ops_struct(fieldtype))
+               if (!is_fptr(fieldtype))
                        return 0;
        }