[SRU][J/L/M][PATCH 1/1] netfilter: nf_tables: bail out on mismatching dynset and set expressions

[Yuxuan Luo]

From: Pablo Neira Ayuso <pablo at netfilter.org>

If dynset expressions provided by userspace is larger than the declared
set expressions, then bail out.

Fixes: 48b0ae046ee9 ("netfilter: nftables: netlink support for several set element expressions")
Reported-by: Xingyuan Mo <hdthky0 at gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
(cherry picked from commit 3701cd390fd731ee7ae8b8006246c8db82c72bea)
CVE-2023-6622
Signed-off-by: Yuxuan Luo <yuxuan.luo at canonical.com>
---
 net/netfilter/nft_dynset.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nft_dynset.c b/net/netfilter/nft_dynset.c
index 5c5cc01c73c5a..629a91a8c6141 100644
--- a/net/netfilter/nft_dynset.c
+++ b/net/netfilter/nft_dynset.c
@@ -279,10 +279,15 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
 			priv->expr_array[i] = dynset_expr;
 			priv->num_exprs++;
 
-			if (set->num_exprs &&
-			    dynset_expr->ops != set->exprs[i]->ops) {
-				err = -EOPNOTSUPP;
-				goto err_expr_free;
+			if (set->num_exprs) {
+				if (i >= set->num_exprs) {
+					err = -EINVAL;
+					goto err_expr_free;
+				}
+				if (dynset_expr->ops != set->exprs[i]->ops) {
+					err = -EOPNOTSUPP;
+					goto err_expr_free;
+				}
 			}
 			i++;
 		}
-- 
2.34.1