linux-kernel - [PATCH] Bluetooth: hci_sync: Prevent unintended PA sync when SID is 0xFF

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Message-Id: <20250807-sid_invalid-v1-1-94b3902a49e3@amlogic.com>
Date: Thu, 07 Aug 2025 15:56:03 +0800
From: Yang Li via B4 Relay <devnull+yang.li.amlogic.com@...nel.org>
To: Marcel Holtmann <marcel@...tmann.org>, 
 Johan Hedberg <johan.hedberg@...il.com>, 
 Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Yang Li <yang.li@...ogic.com>
Subject: [PATCH] Bluetooth: hci_sync: Prevent unintended PA sync when SID
 is 0xFF

From: Yang Li <yang.li@...ogic.com>

After LE Extended Scan times out, conn->sid remains 0xFF,
so the PA sync creation process should be aborted.

Btmon snippet from PA sync with SID=0xFF:

< HCI Command: LE Set Extended.. (0x08|0x0042) plen 6  #74726 [hci0] 863.107927
        Extended scan: Enabled (0x01)
        Filter duplicates: Enabled (0x01)
        Duration: 0 msec (0x0000)
        Period: 0.00 sec (0x0000)
> HCI Event: Command Complete (0x0e) plen 4            #74727 [hci0] 863.109389
      LE Set Extended Scan Enable (0x08|0x0042) ncmd 1
        Status: Success (0x00)
< HCI Command: LE Periodic Ad.. (0x08|0x0044) plen 14  #74728 [hci0] 865.141168
        Options: 0x0000
        Use advertising SID, Advertiser Address Type and address
        Reporting initially enabled
        SID: 0xff
        Adv address type: Random (0x01)
        Adv address: 0D:D7:2C:E7:42:46 (Non-Resolvable)
        Skip: 0x0000
        Sync timeout: 20000 msec (0x07d0)
        Sync CTE type: 0x0000
> HCI Event: Command Status (0x0f) plen 4              #74729 [hci0] 865.143223
      LE Periodic Advertising Create Sync (0x08|0x0044) ncmd 1
        Status: Success (0x00)

Signed-off-by: Yang Li <yang.li@...ogic.com>
---
 net/bluetooth/hci_sync.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 387c128f2ba0..540794a4495f 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7045,10 +7045,13 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)
 	/* SID has not been set listen for HCI_EV_LE_EXT_ADV_REPORT to update
 	 * it.
 	 */
-	if (conn->sid == HCI_SID_INVALID)
-		__hci_cmd_sync_status_sk(hdev, HCI_OP_NOP, 0, NULL,
+	if (conn->sid == HCI_SID_INVALID) {
+		err = __hci_cmd_sync_status_sk(hdev, HCI_OP_NOP, 0, NULL,
 					 HCI_EV_LE_EXT_ADV_REPORT,
 					 conn->conn_timeout, NULL);
+		if (err == -ETIMEDOUT)
+			goto done;
+	}
 
 	memset(&cp, 0, sizeof(cp));
 	cp.options = qos->bcast.options;
@@ -7078,6 +7081,7 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)
 		__hci_cmd_sync_status(hdev, HCI_OP_LE_PA_CREATE_SYNC_CANCEL,
 				      0, NULL, HCI_CMD_TIMEOUT);
 
+done:
 	hci_dev_clear_flag(hdev, HCI_PA_SYNC);
 
 	/* Update passive scan since HCI_PA_SYNC flag has been cleared */

---
base-commit: df18778595f9423542f38784749feca5471f9de7
change-id: 20250807-sid_invalid-2c8b626af2ef

Best regards,
-- 
Yang Li <yang.li@...ogic.com>