From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Wed, 18 Mar 2020 01:14:58 +0100
Subject: netfilter: nf_tables: fix double-free on set expression from the
 error path
Patch-mainline: v5.7-rc1
Git-commit: 772f4e82b3ffa1eb7412cd531f718a96a0e5474b
References: bsc#1176447

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>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/netfilter/nf_tables_api.c |    1 +
 1 file changed, 1 insertion(+)

--- 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_c
 	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);