linux-kernel - [PATCH 4.19 156/211] randstruct: Check member structs in is_pure_ops

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Message-Id: <20191003154523.683939067@linuxfoundation.org>
Date:   Thu,  3 Oct 2019 17:53:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Joonwon Kang <kjw1627@...il.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH 4.19 156/211] randstruct: Check member structs in is_pure_ops_struct()

From: Joonwon Kang <kjw1627@...il.com>

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

---
 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;
 	}