Patch "netfilter: nf_tables: don't skip expired elements during walk" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    netfilter: nf_tables: don't skip expired elements during walk

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-nf_tables-don-t-skip-expired-elements-duri.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e4c9a93b8c5adfc18f7ec04739cc051358951e8d
Author: Florian Westphal <fw@xxxxxxxxx>
Date:   Fri Sep 22 18:30:13 2023 +0200

    netfilter: nf_tables: don't skip expired elements during walk
    
    commit 24138933b97b055d486e8064b4a1721702442a9b upstream.
    
    There is an asymmetry between commit/abort and preparation phase if the
    following conditions are met:
    
    1. set is a verdict map ("1.2.3.4 : jump foo")
    2. timeouts are enabled
    
    In this case, following sequence is problematic:
    
    1. element E in set S refers to chain C
    2. userspace requests removal of set S
    3. kernel does a set walk to decrement chain->use count for all elements
       from preparation phase
    4. kernel does another set walk to remove elements from the commit phase
       (or another walk to do a chain->use increment for all elements from
        abort phase)
    
    If E has already expired in 1), it will be ignored during list walk, so its use count
    won't have been changed.
    
    Then, when set is culled, ->destroy callback will zap the element via
    nf_tables_set_elem_destroy(), but this function is only safe for
    elements that have been deactivated earlier from the preparation phase:
    lack of earlier deactivate removes the element but leaks the chain use
    count, which results in a WARN splat when the chain gets removed later,
    plus a leak of the nft_chain structure.
    
    Update pipapo_get() not to skip expired elements, otherwise flush
    command reports bogus ENOENT errors.
    
    Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
    Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support")
    Fixes: 9d0982927e79 ("netfilter: nft_hash: add support for timeouts")
    Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 3c5cac9bd9b70..475c556f49912 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5386,8 +5386,12 @@ static int nf_tables_dump_setelem(const struct nft_ctx *ctx,
 				  const struct nft_set_iter *iter,
 				  struct nft_set_elem *elem)
 {
+	const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
 	struct nft_set_dump_args *args;
 
+	if (nft_set_elem_expired(ext))
+		return 0;
+
 	args = container_of(iter, struct nft_set_dump_args, iter);
 	return nf_tables_fill_setelem(args->skb, set, elem);
 }
diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index 0b73cb0e752f7..24caa31fa2310 100644
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -278,8 +278,6 @@ static void nft_rhash_walk(const struct nft_ctx *ctx, struct nft_set *set,
 
 		if (iter->count < iter->skip)
 			goto cont;
-		if (nft_set_elem_expired(&he->ext))
-			goto cont;
 		if (!nft_set_elem_active(&he->ext, iter->genmask))
 			goto cont;
 
diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 8c16681884b7e..b6a994ba72f31 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -566,8 +566,7 @@ static struct nft_pipapo_elem *pipapo_get(const struct net *net,
 			goto out;
 
 		if (last) {
-			if (nft_set_elem_expired(&f->mt[b].e->ext) ||
-			    (genmask &&
+			if ((genmask &&
 			     !nft_set_elem_active(&f->mt[b].e->ext, genmask)))
 				goto next_match;
 
@@ -601,8 +600,17 @@ static struct nft_pipapo_elem *pipapo_get(const struct net *net,
 static void *nft_pipapo_get(const struct net *net, const struct nft_set *set,
 			    const struct nft_set_elem *elem, unsigned int flags)
 {
-	return pipapo_get(net, set, (const u8 *)elem->key.val.data,
-			  nft_genmask_cur(net));
+	struct nft_pipapo_elem *ret;
+
+	ret = pipapo_get(net, set, (const u8 *)elem->key.val.data,
+			 nft_genmask_cur(net));
+	if (IS_ERR(ret))
+		return ret;
+
+	if (nft_set_elem_expired(&ret->ext))
+		return ERR_PTR(-ENOENT);
+
+	return ret;
 }
 
 /**
@@ -2024,8 +2032,6 @@ static void nft_pipapo_walk(const struct nft_ctx *ctx, struct nft_set *set,
 			goto cont;
 
 		e = f->mt[r].e;
-		if (nft_set_elem_expired(&e->ext))
-			goto cont;
 
 		elem.priv = e;
 
diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index 8d73fffd2d09d..39956e5341c9e 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -552,8 +552,6 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx,
 
 		if (iter->count < iter->skip)
 			goto cont;
-		if (nft_set_elem_expired(&rbe->ext))
-			goto cont;
 		if (!nft_set_elem_active(&rbe->ext, iter->genmask))
 			goto cont;
 



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