[XFRM]: Prevent off-by-one access to xfrm_dispatch

Makes the type > XFRM_MSG_MAX check behave correctly to
protect access to xfrm_dispatch.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index f0df02ae68a4..4d19b9e65317 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -140,8 +140,9 @@ enum {
         XFRM_MSG_FLUSHPOLICY,
 #define XFRM_MSG_FLUSHPOLICY XFRM_MSG_FLUSHPOLICY
 
-        XFRM_MSG_MAX
+        __XFRM_MSG_MAX
 };
+#define XFRM_MSG_MAX (__XFRM_MSG_MAX - 1)
 
 struct xfrm_user_tmpl {
         struct xfrm_id          id;