Merge tag 'nf-26-03-05' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf

Florian Westphal says:

====================
netfilter: updates for net

1) Inseo An reported a bug with the set element handling in nf_tables:
   When set cannot accept more elements, we unlink and immediately free
   an element that was inserted into a public data structure, freeing it
   without waiting for RCU grace period.  Fix this by doing the
   increment earlier and by deferring possible unlink-and-free to the
   existing abort path, which performs the needed synchronize_rcu before
   free.  From Pablo Neira Ayuso. This is an ancient bug, dating back to
   kernel 4.10.

2) syzbot reported WARN_ON() splat in nf_tables that occurs on memory
   allocation failure.  Fix this by a new iterator annotation:
   The affected walker does not need to clone the data structure and
   can just use the live version if no clone exists yet.
   Also from Pablo.  This bug existed since 6.10 days.

3) Ancient forever bug in nft_pipapo data structure:
   The garbage collection logic to remove expired elements is broken.
   We must unlink from data structure and can only hand the freeing
   to call_rcu after the clone/live pointers of the data structures
   have been swapped.  Else, readers can observe the free'd element.
   Reported by Yiming Qian.

* tag 'nf-26-03-05' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
  netfilter: nf_tables: clone set on flush only
  netfilter: nf_tables: unconditionally bump set->nelems before insertion
====================

Link: https://patch.msgid.link/20260305122635.23525-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 426534a711b0..e2d2bfc1f989 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -320,11 +320,13 @@ static inline void *nft_elem_priv_cast(const struct nft_elem_priv *priv)
  * @NFT_ITER_UNSPEC: unspecified, to catch errors
  * @NFT_ITER_READ: read-only iteration over set elements
  * @NFT_ITER_UPDATE: iteration under mutex to update set element state
+ * @NFT_ITER_UPDATE_CLONE: clone set before iteration under mutex to update element
  */
 enum nft_iter_type {
 	NFT_ITER_UNSPEC,
 	NFT_ITER_READ,
 	NFT_ITER_UPDATE,
+	NFT_ITER_UPDATE_CLONE,
 };
 
 struct nft_set;
@@ -1861,6 +1863,11 @@ struct nft_trans_gc {
 	struct rcu_head		rcu;
 };
 
+static inline int nft_trans_gc_space(const struct nft_trans_gc *trans)
+{
+	return NFT_TRANS_GC_BATCHCOUNT - trans->count;
+}
+
 static inline void nft_ctx_update(struct nft_ctx *ctx,
 				  const struct nft_trans *trans)
 {