IB/core: Avoid leakage from kernel to user space

commit 377b5134 upstream.

Clear the reserved field of struct ib_uverbs_async_event_desc which is
copied to user space.
Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Yann Droneaud <ydroneaud@opteya.com>
(cherry picked from commit 852acc01)
Signed-off-by: Willy Tarreau <w@1wt.eu>

drivers/infiniband/core/uverbs_main.c

@@ -433,6 +433,7 @@ static void ib_uverbs_async_handler(struct ib_uverbs_file *file,
 
 	entry->desc.async.element    = element;
 	entry->desc.async.event_type = event;
+	entry->desc.async.reserved   = 0;
 	entry->counter               = counter;
 
 	list_add_tail(&entry->list, &file->async_file->event_list);