[PATCH libnftnl] set: buffer overflow in NFTNL_SET_DESC_CONCAT setter

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

Allow to set a maximum limit of sizeof(s->desc.field_len) which is 16
bytes, otherwise, bail out. Ensure s->desc.field_count does not go over
the array boundary.

Fixes: 7cd41b5387ac ("set: Add support for NFTA_SET_DESC_CONCAT attributes")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/set.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/set.c b/src/set.c
index 719e59616e97..b51ff9e0ba64 100644
--- a/src/set.c
+++ b/src/set.c
@@ -194,8 +194,14 @@ int nftnl_set_set_data(struct nftnl_set *s, uint16_t attr, const void *data,
 		memcpy(&s->desc.size, data, sizeof(s->desc.size));
 		break;
 	case NFTNL_SET_DESC_CONCAT:
+		if (data_len > sizeof(s->desc.field_len))
+			return -1;
+
 		memcpy(&s->desc.field_len, data, data_len);
-		while (s->desc.field_len[++s->desc.field_count]);
+		while (s->desc.field_len[++s->desc.field_count]) {
+			if (s->desc.field_count >= NFT_REG32_COUNT)
+				break;
+		}
 		break;
 	case NFTNL_SET_TIMEOUT:
 		memcpy(&s->timeout, data, sizeof(s->timeout));
-- 
2.30.2