netfilter: nf_tables: fix double-free on set expression from the error path

After copying the expression to the set element extension, release the
expression and reset the pointer to avoid a double-free from the error
path.

Fixes: 409444522976 ("netfilter: nf_tables: add elements with stateful expressions")
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 f1910cd795fdd35a390ced2462c65a95cc48327b..29ad33e52dbbf30a4c0d5f999559315626f84101 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5133,6 +5133,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
        if (expr) {
                memcpy(nft_set_ext_expr(ext), expr, expr->ops->size);
                kfree(expr);
+               expr = NULL;
        }
 
        trans = nft_trans_elem_alloc(ctx, NFT_MSG_NEWSETELEM, set);