[PATCH nf] netfilter: nf_tables: sanitize nft_set_desc_concat_parse()

[Pablo Neira Ayuso <pablo@netfilter.org>]

Add several sanity checks for nft_set_desc_concat_parse():

- validate desc->field_count not larger than desc->field_len array.
- field length cannot be larger than desc->field_len (ie. U8_MAX)
- total length of the concatenation cannot be larger than register array.

Joint work with Florian Westphal.

Fixes: f3a2181e16f1 ("netfilter: nf_tables: Support for sets with multiple ranged fields")
Reported-by: <zhangziming.zzm@antgroup.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index f4f1d0a2da43..0c7a755dfabb 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4243,8 +4243,11 @@ static int nft_set_desc_concat_parse(const struct nlattr *attr,
 				     struct nft_set_desc *desc)
 {
 	struct nlattr *tb[NFTA_SET_FIELD_MAX + 1];
-	u32 len;
-	int err;
+	u32 len, total = 0;
+	int err, i;
+
+	if (desc->field_count >= ARRAY_SIZE(desc->field_len))
+		return -E2BIG;
 
 	err = nla_parse_nested_deprecated(tb, NFTA_SET_FIELD_MAX, attr,
 					  nft_concat_policy, NULL);
@@ -4255,12 +4258,17 @@ static int nft_set_desc_concat_parse(const struct nlattr *attr,
 		return -EINVAL;
 
 	len = ntohl(nla_get_be32(tb[NFTA_SET_FIELD_LEN]));
-
-	if (len * BITS_PER_BYTE / 32 > NFT_REG32_COUNT)
+	if (len > U8_MAX)
 		return -E2BIG;
 
 	desc->field_len[desc->field_count++] = len;
 
+	for (i = 0; i < desc->field_count; i++)
+		total += desc->field_len[i];
+
+	if (total > U8_MAX || total * BITS_PER_BYTE / 32 > NFT_REG32_COUNT)
+		return -E2BIG;
+
 	return 0;
 }
 
-- 
2.30.2