From: Linus Lüssing linus.luessing@ascom.ch
The rcu protected macros rcu_dereference() and rcu_assign_pointer() for the bat_priv->curr_gw need to be used, as well as spin/rcu locking.
Otherwise we might end up using a curr_gw pointer pointing to already freed memory.
Reported-by: Sven Eckelmann sven@narfation.org Signed-off-by: Linus Lüssing linus.luessing@ascom.ch Signed-off-by: Marek Lindner lindner_marek@yahoo.de --- net/batman-adv/gateway_client.c | 100 +++++++++++++++++++++++++++------------ net/batman-adv/types.h | 4 +- 2 files changed, 72 insertions(+), 32 deletions(-)
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index 517e001..a3e842f 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -44,19 +44,29 @@ static void gw_node_free_ref(struct gw_node *gw_node)
void *gw_get_selected(struct bat_priv *bat_priv) { - struct gw_node *curr_gateway_tmp = bat_priv->curr_gw; + struct gw_node *curr_gateway_tmp; + struct orig_node *orig_node = NULL;
+ rcu_read_lock(); + curr_gateway_tmp = rcu_dereference(bat_priv->curr_gw); if (!curr_gateway_tmp) - return NULL; + goto out; + + orig_node = curr_gateway_tmp->orig_node;
- return curr_gateway_tmp->orig_node; +out: + rcu_read_unlock(); + return orig_node; }
void gw_deselect(struct bat_priv *bat_priv) { - struct gw_node *gw_node = bat_priv->curr_gw; + struct gw_node *gw_node;
- bat_priv->curr_gw = NULL; + spin_lock_bh(&bat_priv->gw_list_lock); + gw_node = rcu_dereference(bat_priv->curr_gw); + rcu_assign_pointer(bat_priv->curr_gw, NULL); + spin_unlock_bh(&bat_priv->gw_list_lock);
if (gw_node) gw_node_free_ref(gw_node); @@ -64,12 +74,15 @@ void gw_deselect(struct bat_priv *bat_priv)
static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node) { - struct gw_node *curr_gw_node = bat_priv->curr_gw; + struct gw_node *curr_gw_node;
if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount)) new_gw_node = NULL;
- bat_priv->curr_gw = new_gw_node; + spin_lock_bh(&bat_priv->gw_list_lock); + curr_gw_node = rcu_dereference(bat_priv->curr_gw); + rcu_assign_pointer(bat_priv->curr_gw, new_gw_node); + spin_unlock_bh(&bat_priv->gw_list_lock);
if (curr_gw_node) gw_node_free_ref(curr_gw_node); @@ -78,7 +91,7 @@ static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node) void gw_election(struct bat_priv *bat_priv) { struct hlist_node *node; - struct gw_node *gw_node, *curr_gw_tmp = NULL; + struct gw_node *gw_node, *curr_gw, *curr_gw_tmp = NULL; uint8_t max_tq = 0; uint32_t max_gw_factor = 0, tmp_gw_factor = 0; int down, up; @@ -92,19 +105,23 @@ void gw_election(struct bat_priv *bat_priv) if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT) return;
- if (bat_priv->curr_gw) + rcu_read_lock(); + curr_gw = rcu_dereference(bat_priv->curr_gw); + if (curr_gw) { + rcu_read_unlock(); return; + }
- rcu_read_lock(); if (hlist_empty(&bat_priv->gw_list)) { - rcu_read_unlock();
- if (bat_priv->curr_gw) { + if (curr_gw) { + rcu_read_unlock(); bat_dbg(DBG_BATMAN, bat_priv, "Removing selected gateway - " "no gateway in range\n"); gw_deselect(bat_priv); - } + } else + rcu_read_unlock();
return; } @@ -153,12 +170,12 @@ void gw_election(struct bat_priv *bat_priv) max_gw_factor = tmp_gw_factor; }
- if (bat_priv->curr_gw != curr_gw_tmp) { - if ((bat_priv->curr_gw) && (!curr_gw_tmp)) + if (curr_gw != curr_gw_tmp) { + if ((curr_gw) && (!curr_gw_tmp)) bat_dbg(DBG_BATMAN, bat_priv, "Removing selected gateway - " "no gateway in range\n"); - else if ((!bat_priv->curr_gw) && (curr_gw_tmp)) + else if ((!curr_gw) && (curr_gw_tmp)) bat_dbg(DBG_BATMAN, bat_priv, "Adding route to gateway %pM " "(gw_flags: %i, tq: %i)\n", @@ -181,31 +198,35 @@ void gw_election(struct bat_priv *bat_priv)
void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node) { - struct gw_node *curr_gateway_tmp = bat_priv->curr_gw; + struct gw_node *curr_gateway_tmp; uint8_t gw_tq_avg, orig_tq_avg;
+ rcu_read_lock(); + curr_gateway_tmp = rcu_dereference(bat_priv->curr_gw); if (!curr_gateway_tmp) - return; + goto out_rcu;
if (!curr_gateway_tmp->orig_node) - goto deselect; + goto deselect_rcu;
if (!curr_gateway_tmp->orig_node->router) - goto deselect; + goto deselect_rcu;
/* this node already is the gateway */ if (curr_gateway_tmp->orig_node == orig_node) - return; + goto out_rcu;
if (!orig_node->router) - return; + goto out_rcu;
gw_tq_avg = curr_gateway_tmp->orig_node->router->tq_avg; + rcu_read_unlock(); + orig_tq_avg = orig_node->router->tq_avg;
/* the TQ value has to be better */ if (orig_tq_avg < gw_tq_avg) - return; + goto out;
/** * if the routing class is greater than 3 the value tells us how much @@ -213,15 +234,23 @@ void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node) **/ if ((atomic_read(&bat_priv->gw_sel_class) > 3) && (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class))) - return; + goto out;
bat_dbg(DBG_BATMAN, bat_priv, "Restarting gateway selection: better gateway found (tq curr: " "%i, tq new: %i)\n", gw_tq_avg, orig_tq_avg); + goto deselect;
+out_rcu: + rcu_read_unlock(); + goto out; +deselect_rcu: + rcu_read_unlock(); deselect: gw_deselect(bat_priv); +out: + return; }
static void gw_node_add(struct bat_priv *bat_priv, @@ -278,7 +307,7 @@ void gw_node_update(struct bat_priv *bat_priv, "Gateway %pM removed from gateway list\n", orig_node->orig);
- if (gw_node == bat_priv->curr_gw) { + if (gw_node == rcu_dereference(bat_priv->curr_gw)) { rcu_read_unlock(); gw_deselect(bat_priv); return; @@ -316,7 +345,7 @@ void gw_node_purge(struct bat_priv *bat_priv) atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE) continue;
- if (bat_priv->curr_gw == gw_node) + if (rcu_dereference(bat_priv->curr_gw) == gw_node) gw_deselect(bat_priv);
hlist_del_rcu(&gw_node->list); @@ -330,12 +359,16 @@ void gw_node_purge(struct bat_priv *bat_priv) static int _write_buffer_text(struct bat_priv *bat_priv, struct seq_file *seq, struct gw_node *gw_node) { - int down, up; + struct gw_node *curr_gw; + int down, up, ret;
gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);
- return seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n", - (bat_priv->curr_gw == gw_node ? "=>" : " "), + rcu_read_lock(); + curr_gw = rcu_dereference(bat_priv->curr_gw); + + ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n", + (curr_gw == gw_node ? "=>" : " "), gw_node->orig_node->orig, gw_node->orig_node->router->tq_avg, gw_node->orig_node->router->addr, @@ -345,6 +378,9 @@ static int _write_buffer_text(struct bat_priv *bat_priv, (down > 2048 ? "MBit" : "KBit"), (up > 2048 ? up / 1024 : up), (up > 2048 ? "MBit" : "KBit")); + + rcu_read_unlock(); + return ret; }
int gw_client_seq_print_text(struct seq_file *seq, void *offset) @@ -465,8 +501,12 @@ int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb) if (atomic_read(&bat_priv->gw_mode) == GW_MODE_SERVER) return -1;
- if (!bat_priv->curr_gw) + rcu_read_lock(); + if (!rcu_dereference(bat_priv->curr_gw)) { + rcu_read_unlock(); return 0; + } + rcu_read_unlock();
return 1; } diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index e1f3e5e..3dd5e77 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -162,7 +162,7 @@ struct bat_priv { spinlock_t forw_bcast_list_lock; /* protects */ spinlock_t hna_lhash_lock; /* protects hna_local_hash */ spinlock_t hna_ghash_lock; /* protects hna_global_hash */ - spinlock_t gw_list_lock; /* protects gw_list */ + spinlock_t gw_list_lock; /* protects gw_list and curr_gw */ spinlock_t vis_hash_lock; /* protects vis_hash */ spinlock_t vis_list_lock; /* protects vis_info::recv_list */ spinlock_t softif_neigh_lock; /* protects soft-interface neigh list */ @@ -171,7 +171,7 @@ struct bat_priv { struct delayed_work hna_work; struct delayed_work orig_work; struct delayed_work vis_work; - struct gw_node *curr_gw; + struct gw_node __rcu *curr_gw; /* rcu protected pointer */ struct vis_info *my_vis_info; };