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@stressinduktion.org>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
index dc0df37..2e710bf 100644
--- a/scripts/gcc-plugins/randomize_layout_plugin.c
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -46,6 +46,8 @@
};
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" },
{ }