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mac80211: mesh: embedd mesh_paths and mpp_paths into ieee80211_if_mesh
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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: 60854fd ("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>
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Pavel Skripkin authored and Johannes Berg committed Jan 4, 2022
1 parent 68a18ad commit 8b5cb7e
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Showing 3 changed files with 54 additions and 81 deletions.
24 changes: 22 additions & 2 deletions net/mac80211/ieee80211_i.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -647,6 +647,26 @@ 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;
Expand Down Expand Up @@ -721,8 +741,8 @@ 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;
};
Expand Down
22 changes: 1 addition & 21 deletions net/mac80211/mesh.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 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 */
};

/* Recent multicast cache */
/* RMC_BUCKETS must be a power of 2, maximum 256 */
#define RMC_BUCKETS 256
Expand Down Expand Up @@ -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);
Expand Down
89 changes: 31 additions & 58 deletions net/mac80211/mesh_pathtbl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}

/**
Expand Down Expand Up @@ -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 *
Expand Down Expand Up @@ -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);
}

/**
Expand All @@ -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);
}

/**
Expand All @@ -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) {
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;

Expand All @@ -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;

Expand Down Expand Up @@ -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);
}

/**
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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
Expand All @@ -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);
}

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