[PKT_SCHED]: Correctly handle empty ematch trees

Fixes an invalid memory reference when the basic classifier
is used without any ematches but just actions.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/net/sched/ematch.c b/net/sched/ematch.c
index ebfe2e7d21bd..64b047c65568 100644
--- a/net/sched/ematch.c
+++ b/net/sched/ematch.c
@@ -298,6 +298,11 @@ int tcf_em_tree_validate(struct tcf_proto *tp, struct rtattr *rta,
         struct tcf_ematch_tree_hdr *tree_hdr;
         struct tcf_ematch *em;
 
+        if (!rta) {
+                memset(tree, 0, sizeof(*tree));
+                return 0;
+        }
+
         if (rtattr_parse_nested(tb, TCA_EMATCH_TREE_MAX, rta) < 0)
                 goto errout;