linux-kernel - [PATCH] randstruct: fix a bug in is_pure_ops

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Date:   Sun, 28 Jul 2019 00:58:41 +0900
From:   Joonwon Kang <kjw1627@...il.com>
To:     keescook@...omium.org
Cc:     re.emese@...il.com, kernel-hardening@...ts.openwall.com,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] randstruct: fix a bug in is_pure_ops_struct()

Before this, there were false negatives in the case 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@...il.com>
---
 scripts/gcc-plugins/randomize_layout_plugin.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
index 6d5bbd31db7f..a123282a4fcd 100644
--- a/scripts/gcc-plugins/randomize_layout_plugin.c
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -443,13 +443,12 @@ 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)
-			continue;
+		if (code == RECORD_TYPE || code == UNION_TYPE) {
+			if (!is_pure_ops_struct(fieldtype))
+				return 0;
+		}
 
-		if (!is_pure_ops_struct(fieldtype))
+		if (!is_fptr(fieldtype))
 			return 0;
 	}
 
-- 
2.17.1