[PATCH] net: bonding: avoid use-after-free with tx_hashtbl/rx_hashtbl

sujing
2023-03-28T03:41:28Z

In bonding mode 6 (Balance-alb),
there are some potential race conditions between the 'bond_close' process
and the tx/rx processes that use tx_hashtbl/rx_hashtbl,
which may lead to use-after-free.

For instance, when the bond6 device is in the 'bond_close' process
while some backlogged packets from upper level are transmitted
to 'bond_start_xmit', there is a spinlock contention between
'tlb_deinitialize' and 'tlb_choose_channel'.

If 'tlb_deinitialize' preempts the lock before 'tlb_choose_channel',
a NULL pointer kernel panic will be triggered.

Here's the timeline:

bond_close ------------------ bond_start_xmit
bond_alb_deinitialize ------- __bond_start_xmit
tlb_deinitialize ------------ bond_alb_xmit
spin_lock_bh ---------------- bond_xmit_alb_slave_get
tx_hashtbl = NULL ----------- tlb_choose_channel
spin_unlock_bh -------------- //wait for spin_lock_bh
------------------------------ spin_lock_bh
------------------------------ __tlb_choose_channel
causing kernel panic ========> tx_hashtbl[hash_index].tx_slave
------------------------------ spin_unlock_bh

Signed-off-by: sujing <sujing@kylinos.cn>
---
drivers/net/bonding/bond_alb.c | 32 +++++++++------------------
drivers/net/bonding/bond_main.c | 39 +++++++++++++++++++++++++++------
include/net/bond_alb.h | 5 ++++-
3 files changed, 46 insertions(+), 30 deletions(-)

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index b9dbad3a8af8..f6ff5ea835c4 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -71,7 +71,7 @@ static inline u8 _simple_hash(const u8 *hash_start, int hash_size)

/*********************** tlb specific functions ***************************/

-static inline void tlb_init_table_entry(struct tlb_client_info *entry, int save_load)
+void tlb_init_table_entry(struct tlb_client_info *entry, int save_load)
{
if (save_load) {
entry->load_history = 1 + entry->tx_bytes /
@@ -269,8 +269,8 @@ static void rlb_update_entry_from_arp(struct bonding *bond, struct arp_pkt *arp)
spin_unlock_bh(&bond->mode_lock);
}

-static int rlb_arp_recv(const struct sk_buff *skb, struct bonding *bond,
- struct slave *slave)
+int rlb_arp_recv(const struct sk_buff *skb, struct bonding *bond,
+ struct slave *slave)
{
struct arp_pkt *arp, _arp;

@@ -756,7 +756,7 @@ static void rlb_init_table_entry_src(struct rlb_client_info *entry)
entry->src_next = RLB_NULL_INDEX;
}

-static void rlb_init_table_entry(struct rlb_client_info *entry)
+void rlb_init_table_entry(struct rlb_client_info *entry)
{
memset(entry, 0, sizeof(struct rlb_client_info));
rlb_init_table_entry_dst(entry);
@@ -874,9 +874,6 @@ static int rlb_initialize(struct bonding *bond)

spin_unlock_bh(&bond->mode_lock);

- /* register to receive ARPs */
- bond->recv_probe = rlb_arp_recv;
-
return 0;
}

@@ -888,7 +885,6 @@ static void rlb_deinitialize(struct bonding *bond)

kfree(bond_info->rx_hashtbl);
bond_info->rx_hashtbl = NULL;
- bond_info->rx_hashtbl_used_head = RLB_NULL_INDEX;

spin_unlock_bh(&bond->mode_lock);
}
@@ -1303,7 +1299,7 @@ static bool alb_determine_nd(struct sk_buff *skb, struct bonding *bond)

/************************ exported alb functions ************************/

-int bond_alb_initialize(struct bonding *bond, int rlb_enabled)
+int bond_alb_initialize(struct bonding *bond)
{
int res;

@@ -1311,15 +1307,10 @@ int bond_alb_initialize(struct bonding *bond, int rlb_enabled)
if (res)
return res;

- if (rlb_enabled) {
- res = rlb_initialize(bond);
- if (res) {
- tlb_deinitialize(bond);
- return res;
- }
- bond->alb_info.rlb_enabled = 1;
- } else {
- bond->alb_info.rlb_enabled = 0;
+ res = rlb_initialize(bond);
+ if (res) {
+ tlb_deinitialize(bond);
+ return res;
}

return 0;
@@ -1327,12 +1318,9 @@ int bond_alb_initialize(struct bonding *bond, int rlb_enabled)

void bond_alb_deinitialize(struct bonding *bond)
{
- struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
-
tlb_deinitialize(bond);

- if (bond_info->rlb_enabled)
- rlb_deinitialize(bond);
+ rlb_deinitialize(bond);
}

static netdev_tx_t bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond,
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 236e5219c811..8fcb5d3ac0a2 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4217,6 +4217,7 @@ static int bond_open(struct net_device *bond_dev)
struct bonding *bond = netdev_priv(bond_dev);
struct list_head *iter;
struct slave *slave;
+ int i;

if (BOND_MODE(bond) == BOND_MODE_ROUNDROBIN && !bond->rr_tx_counter) {
bond->rr_tx_counter = alloc_percpu(u32);
@@ -4239,11 +4240,29 @@ static int bond_open(struct net_device *bond_dev)
}

if (bond_is_lb(bond)) {
- /* bond_alb_initialize must be called before the timer
- * is started.
- */
- if (bond_alb_initialize(bond, (BOND_MODE(bond) == BOND_MODE_ALB)))
- return -ENOMEM;
+ struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
+
+ spin_lock_bh(&bond->mode_lock);
+
+ for (i = 0; i < TLB_HASH_TABLE_SIZE; i++)
+ tlb_init_table_entry(&bond_info->tx_hashtbl[i], 0);
+
+ spin_unlock_bh(&bond->mode_lock);
+
+ if (BOND_MODE(bond) == BOND_MODE_ALB) {
+ bond->alb_info.rlb_enabled = 1;
+ spin_lock_bh(&bond->mode_lock);
+
+ bond_info->rx_hashtbl_used_head = RLB_NULL_INDEX;
+ for (i = 0; i < RLB_HASH_TABLE_SIZE; i++)
+ rlb_init_table_entry(bond_info->rx_hashtbl + i);
+
+ spin_unlock_bh(&bond->mode_lock);
+ bond->recv_probe = rlb_arp_recv;
+ } else {
+ bond->alb_info.rlb_enabled = 0;
+ }
+
if (bond->params.tlb_dynamic_lb || BOND_MODE(bond) == BOND_MODE_ALB)
queue_delayed_work(bond->wq, &bond->alb_work, 0);
}
@@ -4279,8 +4298,6 @@ static int bond_close(struct net_device *bond_dev)

bond_work_cancel_all(bond);
bond->send_peer_notif = 0;
- if (bond_is_lb(bond))
- bond_alb_deinitialize(bond);
bond->recv_probe = NULL;

if (bond_uses_primary(bond)) {
@@ -5854,6 +5871,8 @@ static void bond_uninit(struct net_device *bond_dev)
struct list_head *iter;
struct slave *slave;

+ bond_alb_deinitialize(bond);
+
bond_netpoll_cleanup(bond_dev);

/* Release the bonded slaves */
@@ -6295,6 +6314,12 @@ static int bond_init(struct net_device *bond_dev)
bond_dev->addr_assign_type == NET_ADDR_PERM)
eth_hw_addr_random(bond_dev);

+ /* bond_alb_initialize must be called before the timer
+ * is started.
+ */
+ if (bond_alb_initialize(bond))
+ return -ENOMEM;
+
return 0;
}

diff --git a/include/net/bond_alb.h b/include/net/bond_alb.h
index 9dc082b2d543..9fd16e20ef82 100644
--- a/include/net/bond_alb.h
+++ b/include/net/bond_alb.h
@@ -150,7 +150,7 @@ struct alb_bond_info {
*/
};

-int bond_alb_initialize(struct bonding *bond, int rlb_enabled);
+int bond_alb_initialize(struct bonding *bond);
void bond_alb_deinitialize(struct bonding *bond);
int bond_alb_init_slave(struct bonding *bond, struct slave *slave);
void bond_alb_deinit_slave(struct bonding *bond, struct slave *slave);
@@ -165,5 +165,8 @@ struct slave *bond_xmit_tlb_slave_get(struct bonding *bond,
void bond_alb_monitor(struct work_struct *);
int bond_alb_set_mac_address(struct net_device *bond_dev, void *addr);
void bond_alb_clear_vlan(struct bonding *bond, unsigned short vlan_id);
+int rlb_arp_recv(const struct sk_buff *skb, struct bonding *bond, struct slave *slave);
+void tlb_init_table_entry(struct tlb_client_info *entry, int save_load);
+void rlb_init_table_entry(struct rlb_client_info *entry);
#endif /* _NET_BOND_ALB_H */

--
2.27.0