[PATCH nf,v2] netfilter: nf_tables: mark set as dead when deactivating anonymous set with timeout

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

While the rhashtable set gc runs asynchronously, a race allows it to
collect elements from anonymous sets while it is being released from the
abort, commit and rule error path.

Mingi Cho originally reported this issue in a different path in 6.1.x
with a pipapo set with low timeouts which is not possible upstream since
7395dfacfff6 ("netfilter: nf_tables: use timestamp to check for set
element timeout").

Fix this by setting on the dead flag for anonymous sets to signal set gc
to skip sets from prepare_error, abort and commit paths.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Reported-by: Mingi Cho <mgcho.minic@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v2: handle only anonymous sets per Florian Westphal.

 net/netfilter/nf_tables_api.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fb07455143a5..52d76cc937c9 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5430,6 +5430,7 @@ static void nf_tables_unbind_set(const struct nft_ctx *ctx, struct nft_set *set,
 
 	if (list_empty(&set->bindings) && nft_set_is_anonymous(set)) {
 		list_del_rcu(&set->list);
+		set->dead = 1;
 		if (event)
 			nf_tables_set_notify(ctx, set, NFT_MSG_DELSET,
 					     GFP_KERNEL);
@@ -5500,10 +5501,12 @@ void nf_tables_deactivate_set(const struct nft_ctx *ctx, struct nft_set *set,
 	switch (phase) {
 	case NFT_TRANS_PREPARE_ERROR:
 		nft_set_trans_unbind(ctx, set);
-		if (nft_set_is_anonymous(set))
+		if (nft_set_is_anonymous(set)) {
+			set->dead = 1;
 			nft_deactivate_next(ctx->net, set);
-		else
+		} else {
 			list_del_rcu(&binding->list);
+		}
 
 		nft_use_dec(&set->use);
 		break;
-- 
2.30.2