net: cls_flower: Remove filter from mask before freeing it

In fl_change(), when adding a new rule (i.e. fold == NULL), a driver may
reject the new rule, for example due to resource exhaustion. By that
point, the new rule was already assigned a mask, and it was added to
that mask's hash table. The clean-up path that's invoked as a result of
the rejection however neglects to undo the hash table addition, and
proceeds to free the new rule, thus leaving a dangling pointer in the
hash table.

Fix by removing fnew from the mask's hash table before it is freed.

Fixes: 35cc3cefc4de ("net/sched: cls_flower: Reject duplicated rules also under skip_sw")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index f6aa57fbbbaff96ea8df59c639a1fc575fa2c25b..12ca9d13db83320b6fe3381b1874206dec433a74 100644 (file)
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1371,7 +1371,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
        if (!tc_skip_hw(fnew->flags)) {
                err = fl_hw_replace_filter(tp, fnew, extack);
                if (err)
-                       goto errout_mask;
+                       goto errout_mask_ht;
        }
 
        if (!tc_in_hw(fnew->flags))
@@ -1401,6 +1401,10 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
        kfree(mask);
        return 0;
 
+errout_mask_ht:
+       rhashtable_remove_fast(&fnew->mask->ht, &fnew->ht_node,
+                              fnew->mask->filter_ht_params);
+
 errout_mask:
        fl_mask_put(head, fnew->mask, false);