[PATCH 6.18 009/198] Bluetooth: hci_sync: annotate data-races around hdev->req_status

Greg Kroah-Hartman
2026-04-20T15:57:47Z

From: Cen Zhang <zzzccc427@gmail.com>

[ Upstream commit b6807cfc195ef99e1ac37b2e1e60df40295daa8c ]

__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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bluetooth/hci_conn.c | 2 +-
net/bluetooth/hci_core.c | 2 +-
net/bluetooth/hci_sync.c | 20 ++++++++++----------
3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 24b71ec8897ff..71a24be2a6d67 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2967,7 +2967,7 @@ 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:
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 8ccec73dce45c..0f86b81b39730 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -4125,7 +4125,7 @@ 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);
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 9a7bd4a4b14c4..f498ab28f1aa0 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -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);
}
--
2.53.0