[SRU][J][PATCH 1/3] netfilter: nf_tables: always increment set element count

[Ian Whitfield]

From: Florian Westphal <fw at strlen.de>

At this time, set->nelems counter only increments when the set has
a maximum size.

All set elements decrement the counter unconditionally, this is
confusing.

Increment the counter unconditionally to make this symmetrical.
This would also allow changing the set maximum size after set creation
in a later patch.

Signed-off-by: Florian Westphal <fw at strlen.de>
(cherry picked from commit d4b7f29eb85c93893bc27388b37709efbc3c9a0e)
CVE-2026-23272
Signed-off-by: Ian Whitfield <ian.whitfield at canonical.com>
---
 net/netfilter/nf_tables_api.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 49fc22db42d6..8abe3bd7e97f 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6575,10 +6575,13 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
 		goto err_element_clash;
 	}
 
-	if (!(flags & NFT_SET_ELEM_CATCHALL) && set->size &&
-	    !atomic_add_unless(&set->nelems, 1, set->size + set->ndeact)) {
-		err = -ENFILE;
-		goto err_set_full;
+	if (!(flags & NFT_SET_ELEM_CATCHALL)) {
+		unsigned int max = set->size ? set->size + set->ndeact : UINT_MAX;
+
+		if (!atomic_add_unless(&set->nelems, 1, max)) {
+			err = -ENFILE;
+			goto err_set_full;
+		}
 	}
 
 	nft_trans_elem(trans) = elem;
-- 
2.43.0