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Bluetooth: hci_sync: annotate data-races around hdev->req_status

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__hci_cmd_sync_sk() sets hdev->req_status under hdev->req_lock:

    hdev->req_status = HCI_REQ_PEND;

However, several other functions read or write hdev->req_status without
holding any lock:

  - hci_send_cmd_sync() reads req_status in hci_cmd_work (workqueue)
  - hci_cmd_sync_complete() reads/writes from HCI event completion
  - hci_cmd_sync_cancel() / hci_cmd_sync_cancel_sync() read/write
  - hci_abort_conn() reads in connection abort path

Since __hci_cmd_sync_sk() runs on hdev->req_workqueue while
hci_send_cmd_sync() runs on hdev->workqueue, these are different
workqueues that can execute concurrently on different CPUs. The plain
C accesses constitute a data race.

Add READ_ONCE()/WRITE_ONCE() annotations on all concurrent accesses
to hdev->req_status to prevent potential compiler optimizations that
could affect correctness (e.g., load fusing in the wait_event
condition or store reordering).

Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This commit is contained in:
Cen Zhang 2026-03-15 20:07:26 +08:00 committed by Luiz Augusto von Dentz
parent 5f5fa4cd35
commit b6807cfc19
3 changed files with 12 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/bluetooth/hci_conn.c
View File

@ -3095,7 +3095,7 @@ int hci_abort_conn(struct hci_conn *conn, u8 reason)
* hci_connect_le serializes the connection attempts so only one
* connection can be in BT_CONNECT at time.
*/
if (conn->state == BT_CONNECT && hdev->req_status == HCI_REQ_PEND) {
if (conn->state == BT_CONNECT && READ_ONCE(hdev->req_status) == HCI_REQ_PEND) {
switch (hci_skb_event(hdev->sent_cmd)) {
case HCI_EV_CONN_COMPLETE:
case HCI_EV_LE_CONN_COMPLETE:

2
net/bluetooth/hci_core.c
View File

@ -4126,7 +4126,7 @@ static int hci_send_cmd_sync(struct hci_dev *hdev, struct sk_buff *skb)
kfree_skb(skb);
}
if (hdev->req_status == HCI_REQ_PEND &&
if (READ_ONCE(hdev->req_status) == HCI_REQ_PEND &&
!hci_dev_test_and_set_flag(hdev, HCI_CMD_PENDING)) {
kfree_skb(hdev->req_skb);
hdev->req_skb = skb_clone(hdev->sent_cmd, GFP_KERNEL);

20
net/bluetooth/hci_sync.c
View File

@ -25,11 +25,11 @@ static void hci_cmd_sync_complete(struct hci_dev *hdev, u8 result, u16 opcode,
{
bt_dev_dbg(hdev, "result 0x%2.2x", result);
if (hdev->req_status != HCI_REQ_PEND)
if (READ_ONCE(hdev->req_status) != HCI_REQ_PEND)
return;
hdev->req_result = result;
hdev->req_status = HCI_REQ_DONE;
WRITE_ONCE(hdev->req_status, HCI_REQ_DONE);
/* Free the request command so it is not used as response */
kfree_skb(hdev->req_skb);
@ -167,20 +167,20 @@ struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
hci_cmd_sync_add(&req, opcode, plen, param, event, sk);
hdev->req_status = HCI_REQ_PEND;
WRITE_ONCE(hdev->req_status, HCI_REQ_PEND);
err = hci_req_sync_run(&req);
if (err < 0)
return ERR_PTR(err);
err = wait_event_interruptible_timeout(hdev->req_wait_q,
hdev->req_status != HCI_REQ_PEND,
READ_ONCE(hdev->req_status) != HCI_REQ_PEND,
timeout);
if (err == -ERESTARTSYS)
return ERR_PTR(-EINTR);
switch (hdev->req_status) {
switch (READ_ONCE(hdev->req_status)) {
case HCI_REQ_DONE:
err = -bt_to_errno(hdev->req_result);
break;
@ -194,7 +194,7 @@ struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
break;
}
hdev->req_status = 0;
WRITE_ONCE(hdev->req_status, 0);
hdev->req_result = 0;
skb = hdev->req_rsp;
hdev->req_rsp = NULL;
@ -665,9 +665,9 @@ void hci_cmd_sync_cancel(struct hci_dev *hdev, int err)
{
bt_dev_dbg(hdev, "err 0x%2.2x", err);
if (hdev->req_status == HCI_REQ_PEND) {
if (READ_ONCE(hdev->req_status) == HCI_REQ_PEND) {
hdev->req_result = err;
hdev->req_status = HCI_REQ_CANCELED;
WRITE_ONCE(hdev->req_status, HCI_REQ_CANCELED);
queue_work(hdev->workqueue, &hdev->cmd_sync_cancel_work);
}
@ -683,12 +683,12 @@ void hci_cmd_sync_cancel_sync(struct hci_dev *hdev, int err)
{
bt_dev_dbg(hdev, "err 0x%2.2x", err);
if (hdev->req_status == HCI_REQ_PEND) {
if (READ_ONCE(hdev->req_status) == HCI_REQ_PEND) {
/* req_result is __u32 so error must be positive to be properly
* propagated.
*/
hdev->req_result = err < 0 ? -err : err;
hdev->req_status = HCI_REQ_CANCELED;
WRITE_ONCE(hdev->req_status, HCI_REQ_CANCELED);
wake_up_interruptible(&hdev->req_wait_q);
}