linux-kernel - Re: [PATCH] Bluetooth: hci_sync: use HCI_CMD

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <baca64ce-add3-4937-a4ce-1e372942e91b@amlogic.com>
Date: Fri, 9 Jan 2026 11:06:37 +0800
From: Yang Li <yang.li@...ogic.com>
To: Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: Marcel Holtmann <marcel@...tmann.org>,
 Johan Hedberg <johan.hedberg@...il.com>, linux-bluetooth@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: hci_sync: use HCI_CMD_TIMEOUT for PA sync
 commands

Hi Luiz
> [ EXTERNAL EMAIL ]
>
> Hi Yang,
>
> On Thu, Jan 8, 2026 at 1:03 AM Yang Li via B4 Relay
> <devnull+yang.li.amlogic.com@...nel.org> wrote:
>> From: Yang Li <yang.li@...ogic.com>
>>
>> PA sync HCI commands incorrectly use conn->conn_timeout, which defaults
>> to 20s and is too long. If the PA Sync Established event is not
>> received, the command remains pending and causes userspace timeouts.
> Im pretty sure this is impossible scenario with bluetooth-next, since
> 1. only one work can be running hci_le_pa_create_sync at time so
> HCI_EV_LE_PA_SYNC_ESTABLISHED cannot be outstanding 2. The
> conn->timeout shall be aligned with socket timeout so perhaps the
> problem is userspace is not setting the socket timeout correctly or
> something.


Well, I got it.

I noticed that BlueZ has a default setting for sync_time with the value 
BT_ISO_SYNC_TIMEOUT=0x07d0 /* 20 secs */.

I would like to know the rationale behind setting it to 20 seconds 
initially. This value seems a bit long to me. Can I directly change this 
value as:

BT_ISO_SYNC_TIMEOUT=0x00C8 /* 2 secs */

>> Signed-off-by: Yang Li <yang.li@...ogic.com>
>> ---
>>   net/bluetooth/hci_sync.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
>> index f04a90bce4a9..58292b01f062 100644
>> --- a/net/bluetooth/hci_sync.c
>> +++ b/net/bluetooth/hci_sync.c
>> @@ -7159,7 +7159,7 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)
>>          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);
>> +                                              HCI_CMD_TIMEOUT, NULL);
>>                  if (err == -ETIMEDOUT)
>>                          goto done;
>>          }
>> @@ -7187,7 +7187,7 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)
>>          err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_PA_CREATE_SYNC,
>>                                         sizeof(cp), &cp,
>>                                         HCI_EV_LE_PA_SYNC_ESTABLISHED,
>> -                                      conn->conn_timeout, NULL);
>> +                                      HCI_CMD_TIMEOUT, NULL);
>>          if (err == -ETIMEDOUT)
>>                  __hci_cmd_sync_status(hdev, HCI_OP_LE_PA_CREATE_SYNC_CANCEL,
>>                                        0, NULL, HCI_CMD_TIMEOUT);
>>
>> ---
>> base-commit: bdb9aba465a85122bcba01a6154e237b9843e25b
>> change-id: 20260108-pa_sync_cmd_timeout-ff46f67b5d2a
>>
>> Best regards,
>> --
>> Yang Li <yang.li@...ogic.com>
>>
>>
>
> --
> Luiz Augusto von Dentz