From ee3aadc43ea69d98f666431e787137ac0badbb85 Mon Sep 17 00:00:00 2001 From: Zihan Xi Date: Fri, 18 Sep 2026 05:26:51 +0000 Subject: [PATCH] wifi: mac80211: fix mesh fast xmit path deletion UAF mesh_fast_tx_cache() stores raw mesh_path pointers. Path deletion flushes the cache and then frees the path with kfree_rcu(), but a lookup that already holds the path can insert a new cache entry after the flush. The cache then points at freed memory. Set MESH_PATH_DELETED before flushing, and skip inserting a cache entry if the path or MPP path is already deleted. Check this under the cache walk lock so it is ordered with the flush. Use WRITE_ONCE() for the deletion flag updates because the cache check reads flags without taking state_lock. Fixes: d5edb9ae8d56 ("wifi: mac80211: mesh fast xmit support") Cc: stable@vger.kernel.org Reported-by: Vega Assisted-by: LLM Co-developed-by: Luxing Yin Signed-off-by: Luxing Yin Signed-off-by: Zihan Xi Link: https://patch.msgid.link/1daa7a98199fe6965c2da7c42717073a6fd39a0b.1789615568.git.zihanx@nebusec.ai Signed-off-by: Johannes Berg --- net/mac80211/mesh_pathtbl.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c index 1c55b14c2ac0..07a21dfa8674 100644 --- a/net/mac80211/mesh_pathtbl.c +++ b/net/mac80211/mesh_pathtbl.c @@ -577,6 +577,12 @@ void mesh_fast_tx_cache(struct ieee80211_sub_if_data *sdata, goto unlock_sta; spin_lock(&cache->walk_lock); + if ((READ_ONCE(mpath->flags) & MESH_PATH_DELETED) || + (mppath && (READ_ONCE(mppath->flags) & MESH_PATH_DELETED))) { + kfree(entry); + goto unlock_cache; + } + prev = rhashtable_lookup_get_insert_fast(&cache->rht, &entry->rhash, fast_tx_rht_params); @@ -808,7 +814,8 @@ static void mesh_path_free_rcu(struct mesh_table *tbl, struct ieee80211_sub_if_data *sdata = mpath->sdata; spin_lock_bh(&mpath->state_lock); - mpath->flags |= MESH_PATH_RESOLVING | MESH_PATH_DELETED; + WRITE_ONCE(mpath->flags, + mpath->flags | MESH_PATH_RESOLVING | MESH_PATH_DELETED); mesh_gate_del(tbl, mpath); spin_unlock_bh(&mpath->state_lock); timer_shutdown_sync(&mpath->timer); @@ -822,6 +829,9 @@ static void __mesh_path_del(struct mesh_table *tbl, struct mesh_path *mpath) { hlist_del_rcu(&mpath->walk_list); rhashtable_remove_fast(&tbl->rhead, &mpath->rhash, mesh_rht_params); + spin_lock_bh(&mpath->state_lock); + WRITE_ONCE(mpath->flags, mpath->flags | MESH_PATH_DELETED); + spin_unlock_bh(&mpath->state_lock); if (tbl == &mpath->sdata->u.mesh.mpp_paths) mesh_fast_tx_flush_addr(mpath->sdata, mpath->dst); else