[PATCH 4.19 156/211] randstruct: Check member structs in is_pure_ops_struct()

From: Greg Kroah-Hartman
Date: Thu Oct 03 2019 - 13:17:21 EST


From: Joonwon Kang <kjw1627@xxxxxxxxx>

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@xxxxxxxxx>
Link: https://lore.kernel.org/r/20190727155841.GA13586@host
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
scripts/gcc-plugins/randomize_layout_plugin.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

--- 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
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;
}