From: Jérémy Jean Date: Sat, 8 Aug 2026 12:40:02 +0000 (+0000) Subject: netfilter: flowtable: publish GC-visible tuple last X-Git-Tag: v7.2~27^2~7^2~2 X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=2014ac62df9d45bb9a004a043e85df7be09ed780;p=thirdparty%2Flinux.git netfilter: flowtable: publish GC-visible tuple last nf_flow_table_iterate() only treats original-direction tuple nodes as owning entries. Publishing the original node first lets GC observe and free a flow while flow_offload_add() is still inserting the reply node. Publish the reply node first and the original node last so GC never sees a partially installed flow. KASAN can trigger slab-use-after-free read and write reports in the flowtable/rhashtable path (rht_deferred_worker, jhash, flow_offload_del, flow_offload_lookup, etc.). Fixes: ac2a66665e23 ("netfilter: add generic flow table infrastructure") Signed-off-by: Jérémy Jean Assisted-by: Codex:gpt-5 Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c index b66e65439341..8b1165f2b5a4 100644 --- a/net/netfilter/nf_flow_table_core.c +++ b/net/netfilter/nf_flow_table_core.c @@ -332,17 +332,18 @@ int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow) flow->timeout = nf_flowtable_time_stamp + flow_offload_get_timeout(flow); err = rhashtable_insert_fast(&flow_table->rhashtable, - &flow->tuplehash[0].node, + &flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].node, nf_flow_offload_rhash_params); if (err < 0) return err; + /* GC only iterates original-direction entries; publish original last. */ err = rhashtable_insert_fast(&flow_table->rhashtable, - &flow->tuplehash[1].node, + &flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].node, nf_flow_offload_rhash_params); if (err < 0) { rhashtable_remove_fast(&flow_table->rhashtable, - &flow->tuplehash[0].node, + &flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].node, nf_flow_offload_rhash_params); return err; }