[PATCH wpan] net: ieee802154: handle iftypes as u32

[Alexander Aring <aahringo@redhat.com>]

This patch fixes an issue that an u32 netlink value is handled as a
signed enum value which doesn't fit into the range of u32 netlink type.
If it's handled as -1 value some BIT() evaluation ends in a
shift-out-of-bounds issue. To solve the issue we set the to u32 max which
is s32 "-1" value to keep backwards compatibility and let the followed enum
values start counting at 0. This brings the compiler to never handle the
enum as signed and a check if the value is above NL802154_IFTYPE_MAX should
filter -1 out.

Fixes: f3ea5e44231a ("ieee802154: add new interface command")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 include/net/nl802154.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/net/nl802154.h b/include/net/nl802154.h
index ddcee128f5d9..145acb8f2509 100644
--- a/include/net/nl802154.h
+++ b/include/net/nl802154.h
@@ -19,6 +19,8 @@
  *
  */
 
+#include <linux/types.h>
+
 #define NL802154_GENL_NAME "nl802154"
 
 enum nl802154_commands {
@@ -150,10 +152,9 @@ enum nl802154_attrs {
 };
 
 enum nl802154_iftype {
-	/* for backwards compatibility TODO */
-	NL802154_IFTYPE_UNSPEC = -1,
+	NL802154_IFTYPE_UNSPEC = (~(__u32)0),
 
-	NL802154_IFTYPE_NODE,
+	NL802154_IFTYPE_NODE = 0,
 	NL802154_IFTYPE_MONITOR,
 	NL802154_IFTYPE_COORD,
 
-- 
2.27.0