[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>

diff --git a/net/sched/ematch.c b/net/sched/ematch.c
index ebfe2e7d21bdff98494baf479c2cca37c4175b99..64b047c65568cafe0912b92f7bb18b7e56031c25 100644 (file)
--- 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;