[PATCH 5.15 24/66] netfilter: nf_tables: sanitize nft_set_desc_concat_parse()

Greg Kroah-Hartman
2022-06-03T18:04:48Z

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

commit fecf31ee395b0295f2d7260aa29946b7605f7c85 upstream.

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>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/nf_tables_api.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4151,6 +4151,9 @@ static int nft_set_desc_concat_parse(con
u32 len;
int err;

+ 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);
if (err < 0)
@@ -4160,9 +4163,8 @@ static int nft_set_desc_concat_parse(con
return -EINVAL;

len = ntohl(nla_get_be32(tb[NFTA_SET_FIELD_LEN]));
-
- if (len * BITS_PER_BYTE / 32 > NFT_REG32_COUNT)
- return -E2BIG;
+ if (!len || len > U8_MAX)
+ return -EINVAL;

desc->field_len[desc->field_count++] = len;

@@ -4173,7 +4175,8 @@ static int nft_set_desc_concat(struct nf
const struct nlattr *nla)
{
struct nlattr *attr;
- int rem, err;
+ u32 num_regs = 0;
+ int rem, err, i;

nla_for_each_nested(attr, nla, rem) {
if (nla_type(attr) != NFTA_LIST_ELEM)
@@ -4184,6 +4187,12 @@ static int nft_set_desc_concat(struct nf
return err;
}

+ for (i = 0; i < desc->field_count; i++)
+ num_regs += DIV_ROUND_UP(desc->field_len[i], sizeof(u32));
+
+ if (num_regs > NFT_REG32_COUNT)
+ return -E2BIG;
+
return 0;
}