netfilter: nf_tables: fix underflow in object reference counter

BugLink: https://bugs.launchpad.net/bugs/2037005
commit d6b478666ffa6d2c25386d78bf1c4640d4da305e upstream.

Since ("netfilter: nf_tables: drop map element references from
preparation phase"), integration with commit protocol is better,
therefore drop the workaround that b91d90368837 ("netfilter: nf_tables:
fix leaking object reference count") provides.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d03d950a8d1ae1581db03118d73b744831ab0639..3c2a48f8b7d0fd87d9f5e160fdec82b063d250ec 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6571,19 +6571,19 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
        if (flags)
                *nft_set_ext_flags(ext) = flags;
 
+       if (obj) {
+               *nft_set_ext_obj(ext) = obj;
+               obj->use++;
+       }
        if (ulen > 0) {
                if (nft_set_ext_check(&tmpl, NFT_SET_EXT_USERDATA, ulen) < 0) {
                        err = -EINVAL;
-                       goto err_elem_userdata;
+                       goto err_elem_free;
                }
                udata = nft_set_ext_userdata(ext);
                udata->len = ulen - 1;
                nla_memcpy(&udata->data, nla[NFTA_SET_ELEM_USERDATA], ulen);
        }
-       if (obj) {
-               *nft_set_ext_obj(ext) = obj;
-               obj->use++;
-       }
        err = nft_set_elem_expr_setup(ctx, &tmpl, ext, expr_array, num_exprs);
        if (err < 0)
                goto err_elem_free;
@@ -6638,9 +6638,6 @@ err_set_full:
 err_element_clash:
        kfree(trans);
 err_elem_free:
-       if (obj)
-               obj->use--;
-err_elem_userdata:
        nft_set_elem_destroy(set, elem.priv, true);
 err_parse_data:
        if (nla[NFTA_SET_ELEM_DATA] != NULL)