netfilter: nf_tables: fix underflow in chain reference counter

Set element addition error path decrements reference counter on chains
twice: once on element release and again via nft_data_release().

Then, d6b478666ffa ("netfilter: nf_tables: fix underflow in object
reference counter") incorrectly fixed this by removing the stateful
object reference count decrement.

Restore the stateful object decrement as in b91d90368837 ("netfilter:
nf_tables: fix leaking object reference count") and let
nft_data_release() decrement the chain reference counter, so this is
done only once.

Fixes: d6b478666ffa ("netfilter: nf_tables: fix underflow in object reference counter")
Fixes: 628bd3e49cba ("netfilter: nf_tables: drop map element references from preparation phase")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 1d64c16..c742918 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6771,7 +6771,9 @@ err_set_full:
 err_element_clash:
        kfree(trans);
 err_elem_free:
-       nft_set_elem_destroy(set, elem.priv, true);
+       nf_tables_set_elem_destroy(ctx, set, elem.priv);
+       if (obj)
+               obj->use--;
 err_parse_data:
        if (nla[NFTA_SET_ELEM_DATA] != NULL)
                nft_data_release(&elem.data.val, desc.type);