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Message-Id: <1495829844-69341-7-git-send-email-keescook@chromium.org>
Date: Fri, 26 May 2017 13:17:10 -0700
From: Kees Cook <keescook@...omium.org>
To: kernel-hardening@...ts.openwall.com
Cc: Kees Cook <keescook@...omium.org>,
Hannes Frederic Sowa <hannes@...essinduktion.org>,
"Signed-off-by : David S . Miller" <davem@...emloft.net>,
Laura Abbott <labbott@...hat.com>,
x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 06/20] randstruct: Whitelist UNIXCB cast
This is another false positive in bad cast detection:
net/unix/af_unix.c: In function ‘unix_skb_scm_eq’:
net/unix/af_unix.c:1621:31: note: found mismatched rhs struct pointer types: ‘struct unix_skb_parms’ and ‘char’
const struct unix_skb_parms *u = &UNIXCB(skb);
^
UNIXCB is:
#define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb))
And ->cb is:
char cb[48] __aligned(8);
This is a rather crazy cast, but appears to be safe in the face of
randomization, so whitelist it in the plugin.
Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
scripts/gcc-plugins/randomize_layout_plugin.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
index e126ac7874af..bf110915a5aa 100644
--- a/scripts/gcc-plugins/randomize_layout_plugin.c
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -43,6 +43,8 @@ struct whitelist_entry {
};
static const struct whitelist_entry whitelist[] = {
+ /* unix_skb_parms via UNIXCB() buffer */
+ { "net/unix/af_unix.c", "unix_skb_parms", "char" },
/* walk struct security_hook_heads as an array of struct list_head */
{ "security/security.c", "list_head", "security_hook_heads" },
{ }
--
2.7.4
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