From: Pavel Skripkin paskripkin@gmail.com

commit 8b5cb7e41d9d77ffca036b0239177de123394a55 upstream.

Syzbot hit NULL deref in rhashtable_free_and_destroy(). The problem was in mesh_paths and mpp_paths being NULL.

mesh_pathtbl_init() could fail in case of memory allocation failure, but nobody cared, since ieee80211_mesh_init_sdata() returns void. It led to leaving 2 pointers as NULL. Syzbot has found null deref on exit path, but it could happen anywhere else, because code assumes these pointers are valid.

Since all ieee80211_*_setup_sdata functions are void and do not fail, let's embedd mesh_paths and mpp_paths into parent struct to avoid adding error handling on higher levels and follow the pattern of others setup_sdata functions

Fixes: 60854fd94573 ("mac80211: mesh: convert path table to rhashtable") Reported-and-tested-by: syzbot+860268315ba86ea6b96b@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin paskripkin@gmail.com Link: https://lore.kernel.org/r/20211230195547.23977-1-paskripkin@gmail.com Signed-off-by: Johannes Berg johannes.berg@intel.com [pchelkin@ispras.ru: adapt a comment spell fixing issue] Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru --- net/mac80211/ieee80211_i.h | 24 +++++++++- net/mac80211/mesh.h | 22 +-------- net/mac80211/mesh_pathtbl.c | 89 +++++++++++++------------------------ 3 files changed, 54 insertions(+), 81 deletions(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 63499db5c63d..bd349ae9ee4b 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -644,6 +644,26 @@ struct mesh_csa_settings { struct cfg80211_csa_settings settings; };

+/** + * struct mesh_table + * + * @known_gates: list of known mesh gates and their mpaths by the station. The + * gate's mpath may or may not be resolved and active. + * @gates_lock: protects updates to known_gates + * @rhead: the rhashtable containing struct mesh_paths, keyed by dest addr + * @walk_head: linked list containing all mesh_path objects + * @walk_lock: lock protecting walk_head + * @entries: number of entries in the table + */ +struct mesh_table { + struct hlist_head known_gates; + spinlock_t gates_lock; + struct rhashtable rhead; + struct hlist_head walk_head; + spinlock_t walk_lock; + atomic_t entries; /* Up to MAX_MESH_NEIGHBOURS */ +}; + struct ieee80211_if_mesh { struct timer_list housekeeping_timer; struct timer_list mesh_path_timer; @@ -718,8 +738,8 @@ struct ieee80211_if_mesh { /* offset from skb->data while building IE */ int meshconf_offset;

- struct mesh_table *mesh_paths; - struct mesh_table *mpp_paths; /* Store paths for MPP&MAP */ + struct mesh_table mesh_paths; + struct mesh_table mpp_paths; /* Store paths for MPP&MAP */ int mesh_paths_generation; int mpp_paths_generation; }; diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h index 40492d1bd8fd..b2b717a78114 100644 --- a/net/mac80211/mesh.h +++ b/net/mac80211/mesh.h @@ -127,26 +127,6 @@ struct mesh_path { u32 path_change_count; };

-/** - * struct mesh_table - * - * @known_gates: list of known mesh gates and their mpaths by the station. The - * gate's mpath may or may not be resolved and active. - * @gates_lock: protects updates to known_gates - * @rhead: the rhashtable containing struct mesh_paths, keyed by dest addr - * @walk_head: linked list containging all mesh_path objects - * @walk_lock: lock protecting walk_head - * @entries: number of entries in the table - */ -struct mesh_table { - struct hlist_head known_gates; - spinlock_t gates_lock; - struct rhashtable rhead; - struct hlist_head walk_head; - spinlock_t walk_lock; - atomic_t entries; /* Up to MAX_MESH_NEIGHBOURS */ -}; - /* Recent multicast cache */ /* RMC_BUCKETS must be a power of 2, maximum 256 */ #define RMC_BUCKETS 256 @@ -308,7 +288,7 @@ int mesh_path_error_tx(struct ieee80211_sub_if_data *sdata, void mesh_path_assign_nexthop(struct mesh_path *mpath, struct sta_info *sta); void mesh_path_flush_pending(struct mesh_path *mpath); void mesh_path_tx_pending(struct mesh_path *mpath); -int mesh_pathtbl_init(struct ieee80211_sub_if_data *sdata); +void mesh_pathtbl_init(struct ieee80211_sub_if_data *sdata); void mesh_pathtbl_unregister(struct ieee80211_sub_if_data *sdata); int mesh_path_del(struct ieee80211_sub_if_data *sdata, const u8 *addr); void mesh_path_timer(struct timer_list *t); diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c index c2b051e0610a..d936ef0c17a3 100644 --- a/net/mac80211/mesh_pathtbl.c +++ b/net/mac80211/mesh_pathtbl.c @@ -47,32 +47,24 @@ static void mesh_path_rht_free(void *ptr, void *tblptr) mesh_path_free_rcu(tbl, mpath); }

-static struct mesh_table *mesh_table_alloc(void) +static void mesh_table_init(struct mesh_table *tbl) { - struct mesh_table *newtbl; + INIT_HLIST_HEAD(&tbl->known_gates); + INIT_HLIST_HEAD(&tbl->walk_head); + atomic_set(&tbl->entries, 0); + spin_lock_init(&tbl->gates_lock); + spin_lock_init(&tbl->walk_lock);

- newtbl = kmalloc(sizeof(struct mesh_table), GFP_ATOMIC); - if (!newtbl) - return NULL; - - INIT_HLIST_HEAD(&newtbl->known_gates); - INIT_HLIST_HEAD(&newtbl->walk_head); - atomic_set(&newtbl->entries, 0); - spin_lock_init(&newtbl->gates_lock); - spin_lock_init(&newtbl->walk_lock); - if (rhashtable_init(&newtbl->rhead, &mesh_rht_params)) { - kfree(newtbl); - return NULL; - } - - return newtbl; + /* rhashtable_init() may fail only in case of wrong + * mesh_rht_params + */ + WARN_ON(rhashtable_init(&tbl->rhead, &mesh_rht_params)); }

static void mesh_table_free(struct mesh_table *tbl) { rhashtable_free_and_destroy(&tbl->rhead, mesh_path_rht_free, tbl); - kfree(tbl); }

/** @@ -238,13 +230,13 @@ static struct mesh_path *mpath_lookup(struct mesh_table *tbl, const u8 *dst, struct mesh_path * mesh_path_lookup(struct ieee80211_sub_if_data *sdata, const u8 *dst) { - return mpath_lookup(sdata->u.mesh.mesh_paths, dst, sdata); + return mpath_lookup(&sdata->u.mesh.mesh_paths, dst, sdata); }

struct mesh_path * mpp_path_lookup(struct ieee80211_sub_if_data *sdata, const u8 *dst) { - return mpath_lookup(sdata->u.mesh.mpp_paths, dst, sdata); + return mpath_lookup(&sdata->u.mesh.mpp_paths, dst, sdata); }

static struct mesh_path * @@ -281,7 +273,7 @@ __mesh_path_lookup_by_idx(struct mesh_table *tbl, int idx) struct mesh_path * mesh_path_lookup_by_idx(struct ieee80211_sub_if_data *sdata, int idx) { - return __mesh_path_lookup_by_idx(sdata->u.mesh.mesh_paths, idx); + return __mesh_path_lookup_by_idx(&sdata->u.mesh.mesh_paths, idx); }

/** @@ -296,7 +288,7 @@ mesh_path_lookup_by_idx(struct ieee80211_sub_if_data *sdata, int idx) struct mesh_path * mpp_path_lookup_by_idx(struct ieee80211_sub_if_data *sdata, int idx) { - return __mesh_path_lookup_by_idx(sdata->u.mesh.mpp_paths, idx); + return __mesh_path_lookup_by_idx(&sdata->u.mesh.mpp_paths, idx); }

/** @@ -309,7 +301,7 @@ int mesh_path_add_gate(struct mesh_path *mpath) int err;

rcu_read_lock(); - tbl = mpath->sdata->u.mesh.mesh_paths; + tbl = &mpath->sdata->u.mesh.mesh_paths;

spin_lock_bh(&mpath->state_lock); if (mpath->is_gate) { @@ -418,7 +410,7 @@ struct mesh_path *mesh_path_add(struct ieee80211_sub_if_data *sdata, if (!new_mpath) return ERR_PTR(-ENOMEM);

- tbl = sdata->u.mesh.mesh_paths; + tbl = &sdata->u.mesh.mesh_paths; spin_lock_bh(&tbl->walk_lock); mpath = rhashtable_lookup_get_insert_fast(&tbl->rhead, &new_mpath->rhash, @@ -460,7 +452,7 @@ int mpp_path_add(struct ieee80211_sub_if_data *sdata, return -ENOMEM;

memcpy(new_mpath->mpp, mpp, ETH_ALEN); - tbl = sdata->u.mesh.mpp_paths; + tbl = &sdata->u.mesh.mpp_paths;

spin_lock_bh(&tbl->walk_lock); ret = rhashtable_lookup_insert_fast(&tbl->rhead, @@ -489,7 +481,7 @@ int mpp_path_add(struct ieee80211_sub_if_data *sdata, void mesh_plink_broken(struct sta_info *sta) { struct ieee80211_sub_if_data *sdata = sta->sdata; - struct mesh_table *tbl = sdata->u.mesh.mesh_paths; + struct mesh_table *tbl = &sdata->u.mesh.mesh_paths; static const u8 bcast[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; struct mesh_path *mpath;

@@ -548,7 +540,7 @@ static void __mesh_path_del(struct mesh_table *tbl, struct mesh_path *mpath) void mesh_path_flush_by_nexthop(struct sta_info *sta) { struct ieee80211_sub_if_data *sdata = sta->sdata; - struct mesh_table *tbl = sdata->u.mesh.mesh_paths; + struct mesh_table *tbl = &sdata->u.mesh.mesh_paths; struct mesh_path *mpath; struct hlist_node *n;

@@ -563,7 +555,7 @@ void mesh_path_flush_by_nexthop(struct sta_info *sta) static void mpp_flush_by_proxy(struct ieee80211_sub_if_data *sdata, const u8 *proxy) { - struct mesh_table *tbl = sdata->u.mesh.mpp_paths; + struct mesh_table *tbl = &sdata->u.mesh.mpp_paths; struct mesh_path *mpath; struct hlist_node *n;

@@ -597,8 +589,8 @@ static void table_flush_by_iface(struct mesh_table *tbl) */ void mesh_path_flush_by_iface(struct ieee80211_sub_if_data *sdata) { - table_flush_by_iface(sdata->u.mesh.mesh_paths); - table_flush_by_iface(sdata->u.mesh.mpp_paths); + table_flush_by_iface(&sdata->u.mesh.mesh_paths); + table_flush_by_iface(&sdata->u.mesh.mpp_paths); }

/** @@ -644,7 +636,7 @@ int mesh_path_del(struct ieee80211_sub_if_data *sdata, const u8 *addr) /* flush relevant mpp entries first */ mpp_flush_by_proxy(sdata, addr);

- err = table_path_del(sdata->u.mesh.mesh_paths, sdata, addr); + err = table_path_del(&sdata->u.mesh.mesh_paths, sdata, addr); sdata->u.mesh.mesh_paths_generation++; return err; } @@ -682,7 +674,7 @@ int mesh_path_send_to_gates(struct mesh_path *mpath) struct mesh_path *gate; bool copy = false;

- tbl = sdata->u.mesh.mesh_paths; + tbl = &sdata->u.mesh.mesh_paths;

rcu_read_lock(); hlist_for_each_entry_rcu(gate, &tbl->known_gates, gate_list) { @@ -762,29 +754,10 @@ void mesh_path_fix_nexthop(struct mesh_path *mpath, struct sta_info *next_hop) mesh_path_tx_pending(mpath); }

-int mesh_pathtbl_init(struct ieee80211_sub_if_data *sdata) +void mesh_pathtbl_init(struct ieee80211_sub_if_data *sdata) { - struct mesh_table *tbl_path, *tbl_mpp; - int ret; - - tbl_path = mesh_table_alloc(); - if (!tbl_path) - return -ENOMEM; - - tbl_mpp = mesh_table_alloc(); - if (!tbl_mpp) { - ret = -ENOMEM; - goto free_path; - } - - sdata->u.mesh.mesh_paths = tbl_path; - sdata->u.mesh.mpp_paths = tbl_mpp; - - return 0; - -free_path: - mesh_table_free(tbl_path); - return ret; + mesh_table_init(&sdata->u.mesh.mesh_paths); + mesh_table_init(&sdata->u.mesh.mpp_paths); }

static @@ -806,12 +779,12 @@ void mesh_path_tbl_expire(struct ieee80211_sub_if_data *sdata,

void mesh_path_expire(struct ieee80211_sub_if_data *sdata) { - mesh_path_tbl_expire(sdata, sdata->u.mesh.mesh_paths); - mesh_path_tbl_expire(sdata, sdata->u.mesh.mpp_paths); + mesh_path_tbl_expire(sdata, &sdata->u.mesh.mesh_paths); + mesh_path_tbl_expire(sdata, &sdata->u.mesh.mpp_paths); }

void mesh_pathtbl_unregister(struct ieee80211_sub_if_data *sdata) { - mesh_table_free(sdata->u.mesh.mesh_paths); - mesh_table_free(sdata->u.mesh.mpp_paths); + mesh_table_free(&sdata->u.mesh.mesh_paths); + mesh_table_free(&sdata->u.mesh.mpp_paths); }