From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
This reworks hci_cb_list to not use mutex hci_cb_list_lock to avoid bugs
like the bellow:
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:585
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 5070, name: kworker/u9:2
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
4 locks held by kworker/u9:2/5070:
#0: ffff888015be3948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline]
#0: ffff888015be3948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x1770 kernel/workqueue.c:3335
#1: ffffc90003b6fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline]
#1: ffffc90003b6fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x1770 kernel/workqueue.c:3335
#2: ffff8880665d0078 (&hdev->lock){+.+.}-{3:3}, at: hci_le_create_big_complete_evt+0xcf/0xae0 net/bluetooth/hci_event.c:6914
#3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: hci_le_create_big_complete_evt+0xdb/0xae0 net/bluetooth/hci_event.c:6915
CPU: 0 PID: 5070 Comm: kworker/u9:2 Not tainted 6.8.0-syzkaller-08073-g480e035fc4c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: hci0 hci_rx_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
__might_resched+0x5d4/0x780 kernel/sched/core.c:10187
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0xc1/0xd70 kernel/locking/mutex.c:752
hci_connect_cfm include/net/bluetooth/hci_core.h:2004 [inline]
hci_le_create_big_complete_evt+0x3d9/0xae0 net/bluetooth/hci_event.c:6939
hci_event_func net/bluetooth/hci_event.c:7514 [inline]
hci_event_packet+0xa53/0x1540 net/bluetooth/hci_event.c:7569
hci_rx_work+0x3e8/0xca0 net/bluetooth/hci_core.c:4171
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335
worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
</TASK>
Reported-by: syzbot+2fb0835e0c9cefc34614@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=2fb0835e0c9cefc34614
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
include/net/bluetooth/hci_core.h | 89 ++++++++++++++++++++++----------
net/bluetooth/hci_core.c | 9 ++--
2 files changed, 65 insertions(+), 33 deletions(-)
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index ea798f07c5a2..95f11f04e24a 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -804,7 +804,6 @@ struct hci_conn_params {
extern struct list_head hci_dev_list;
extern struct list_head hci_cb_list;
extern rwlock_t hci_dev_list_lock;
-extern struct mutex hci_cb_list_lock;
#define hci_dev_set_flag(hdev, nr) set_bit((nr), (hdev)->dev_flags)
#define hci_dev_clear_flag(hdev, nr) clear_bit((nr), (hdev)->dev_flags)
@@ -2029,12 +2028,18 @@ static inline void hci_connect_cfm(struct hci_conn *conn, __u8 status)
{
struct hci_cb *cb;
- mutex_lock(&hci_cb_list_lock);
- list_for_each_entry(cb, &hci_cb_list, list) {
- if (cb->connect_cfm)
- cb->connect_cfm(conn, status);
+ rcu_read_lock();
+ list_for_each_entry_rcu(cb, &hci_cb_list, list) {
+ if (cb->connect_cfm) {
+ struct hci_cb cpy = *cb;
+
+ /* Callback may block so release RCU read lock */
+ rcu_read_unlock();
+ cpy.connect_cfm(conn, status);
+ rcu_read_lock();
+ }
}
- mutex_unlock(&hci_cb_list_lock);
+ rcu_read_unlock();
if (conn->connect_cfm_cb)
conn->connect_cfm_cb(conn, status);
@@ -2044,12 +2049,18 @@ static inline void hci_disconn_cfm(struct hci_conn *conn, __u8 reason)
{
struct hci_cb *cb;
- mutex_lock(&hci_cb_list_lock);
+ rcu_read_lock();
list_for_each_entry(cb, &hci_cb_list, list) {
- if (cb->disconn_cfm)
- cb->disconn_cfm(conn, reason);
+ if (cb->disconn_cfm) {
+ struct hci_cb cpy = *cb;
+
+ /* Callback may block so release RCU read lock */
+ rcu_read_unlock();
+ cpy.disconn_cfm(conn, reason);
+ rcu_read_lock();
+ }
}
- mutex_unlock(&hci_cb_list_lock);
+ rcu_read_unlock();
if (conn->disconn_cfm_cb)
conn->disconn_cfm_cb(conn, reason);
@@ -2065,12 +2076,18 @@ static inline void hci_auth_cfm(struct hci_conn *conn, __u8 status)
encrypt = test_bit(HCI_CONN_ENCRYPT, &conn->flags) ? 0x01 : 0x00;
- mutex_lock(&hci_cb_list_lock);
+ rcu_read_lock();
list_for_each_entry(cb, &hci_cb_list, list) {
- if (cb->security_cfm)
- cb->security_cfm(conn, status, encrypt);
+ if (cb->security_cfm) {
+ struct hci_cb cpy = *cb;
+
+ /* Callback may block so release RCU read lock */
+ rcu_read_unlock();
+ cpy.security_cfm(conn, status, encrypt);
+ rcu_read_lock();
+ }
}
- mutex_unlock(&hci_cb_list_lock);
+ rcu_read_unlock();
if (conn->security_cfm_cb)
conn->security_cfm_cb(conn, status);
@@ -2105,12 +2122,18 @@ static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
conn->sec_level = conn->pending_sec_level;
}
- mutex_lock(&hci_cb_list_lock);
+ rcu_read_lock();
list_for_each_entry(cb, &hci_cb_list, list) {
- if (cb->security_cfm)
- cb->security_cfm(conn, status, encrypt);
+ if (cb->security_cfm) {
+ struct hci_cb cpy = *cb;
+
+ /* Callback may block so release RCU read lock */
+ rcu_read_unlock();
+ cpy.security_cfm(conn, status, encrypt);
+ rcu_read_lock();
+ }
}
- mutex_unlock(&hci_cb_list_lock);
+ rcu_read_unlock();
if (conn->security_cfm_cb)
conn->security_cfm_cb(conn, status);
@@ -2120,12 +2143,18 @@ static inline void hci_key_change_cfm(struct hci_conn *conn, __u8 status)
{
struct hci_cb *cb;
- mutex_lock(&hci_cb_list_lock);
+ rcu_read_lock();
list_for_each_entry(cb, &hci_cb_list, list) {
- if (cb->key_change_cfm)
- cb->key_change_cfm(conn, status);
+ if (cb->key_change_cfm) {
+ struct hci_cb cpy = *cb;
+
+ /* Callback may block so release RCU read lock */
+ rcu_read_unlock();
+ cpy.key_change_cfm(conn, status);
+ rcu_read_lock();
+ }
}
- mutex_unlock(&hci_cb_list_lock);
+ rcu_read_unlock();
}
static inline void hci_role_switch_cfm(struct hci_conn *conn, __u8 status,
@@ -2133,12 +2162,18 @@ static inline void hci_role_switch_cfm(struct hci_conn *conn, __u8 status,
{
struct hci_cb *cb;
- mutex_lock(&hci_cb_list_lock);
- list_for_each_entry(cb, &hci_cb_list, list) {
- if (cb->role_switch_cfm)
- cb->role_switch_cfm(conn, status, role);
+ rcu_read_lock();
+ list_for_each_entry_rcu(cb, &hci_cb_list, list) {
+ if (cb->role_switch_cfm) {
+ struct hci_cb cpy = *cb;
+
+ /* Callback may block so release RCU read lock */
+ rcu_read_unlock();
+ cpy.role_switch_cfm(conn, status, role);
+ rcu_read_lock();
+ }
}
- mutex_unlock(&hci_cb_list_lock);
+ rcu_read_unlock();
}
static inline bool hci_bdaddr_is_rpa(bdaddr_t *bdaddr, u8 addr_type)
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index f9e19f9cb5a3..25d180d225c1 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2993,9 +2993,7 @@ int hci_register_cb(struct hci_cb *cb)
{
BT_DBG("%p name %s", cb, cb->name);
- mutex_lock(&hci_cb_list_lock);
- list_add_tail(&cb->list, &hci_cb_list);
- mutex_unlock(&hci_cb_list_lock);
+ list_add_tail_rcu(&cb->list, &hci_cb_list);
return 0;
}
@@ -3005,9 +3003,8 @@ int hci_unregister_cb(struct hci_cb *cb)
{
BT_DBG("%p name %s", cb, cb->name);
- mutex_lock(&hci_cb_list_lock);
- list_del(&cb->list);
- mutex_unlock(&hci_cb_list_lock);
+ list_del_rcu(&cb->list);
+ synchronize_rcu();
return 0;
}
--
2.47.1
