netfilter: nf_tables: mark set as dead when unbinding anonymous set with timeout

While the rhashtable set gc runs asynchronously, a race allows it to
collect elements from anonymous sets with timeouts while it is being
released from the commit 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 skip async gc
in this case.

According to 08e4c8c5919f ("netfilter: nf_tables: mark newset as dead on
transaction abort"), Florian plans to accelerate abort path by releasing
objects via workqueue, therefore, this sets on the dead flag for abort
path too.

Cc: stable@vger.kernel.org
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>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fb07455..1683dc1 100644 (file)
--- 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);