linux-kernel - Re: [PATCH v2] Bluetooth: hci_sync: fix set_local

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Message-ID: <0c85712e-0a94-434b-998e-5713e6ec491b@molgen.mpg.de>
Date: Fri, 22 Aug 2025 12:22:21 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Pavel Shpakovskiy <pashpakovskii@...utedevices.com>
Cc: marcel@...tmann.org, johan.hedberg@...il.com, luiz.dentz@...il.com,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, horms@...nel.org, linux-bluetooth@...r.kernel.org,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel@...utedevices.com
Subject: Re: [PATCH v2] Bluetooth: hci_sync: fix set_local_name race condition

[Cc: remove bouncing brian.gix@...el.com]

Dear Pavel,


Thank you for the improved version.

Am 22.08.25 um 11:20 schrieb Pavel Shpakovskiy:
> Function set_name_sync() uses hdev->dev_name field to send
> HCI_OP_WRITE_LOCAL_NAME command, but copying from data to hdev->dev_name
> is called after mgmt cmd was queued, so it is possible that function
> set_name_sync() will read old name value.
> 
> This change adds name as a parameter for function hci_update_name_sync()
> to avoid race condition.
> 
> Fixes: 6f6ff38a1e14 ("Bluetooth: hci_sync: Convert MGMT_OP_SET_LOCAL_NAME")
> Signed-off-by: Pavel Shpakovskiy <pashpakovskii@...utedevices.com>
> ---
>   Changelog v1->v2:
>   * Fix some minor style comments for commit messsage.
> 
>   include/net/bluetooth/hci_sync.h | 2 +-
>   net/bluetooth/hci_sync.c         | 6 +++---
>   net/bluetooth/mgmt.c             | 5 ++++-
>   3 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/include/net/bluetooth/hci_sync.h b/include/net/bluetooth/hci_sync.h
> index 72558c826aa1b..eef12830eaec9 100644
> --- a/include/net/bluetooth/hci_sync.h
> +++ b/include/net/bluetooth/hci_sync.h
> @@ -93,7 +93,7 @@ int hci_update_class_sync(struct hci_dev *hdev);
>   
>   int hci_update_eir_sync(struct hci_dev *hdev);
>   int hci_update_class_sync(struct hci_dev *hdev);
> -int hci_update_name_sync(struct hci_dev *hdev);
> +int hci_update_name_sync(struct hci_dev *hdev, const u8 *name);
>   int hci_write_ssp_mode_sync(struct hci_dev *hdev, u8 mode);
>   
>   int hci_get_random_address(struct hci_dev *hdev, bool require_privacy,
> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> index e56b1cbedab90..c2a6469e81cdf 100644
> --- a/net/bluetooth/hci_sync.c
> +++ b/net/bluetooth/hci_sync.c
> @@ -3412,13 +3412,13 @@ int hci_update_scan_sync(struct hci_dev *hdev)
>   	return hci_write_scan_enable_sync(hdev, scan);
>   }
>   
> -int hci_update_name_sync(struct hci_dev *hdev)
> +int hci_update_name_sync(struct hci_dev *hdev, const u8 *name)
>   {
>   	struct hci_cp_write_local_name cp;
>   
>   	memset(&cp, 0, sizeof(cp));
>   
> -	memcpy(cp.name, hdev->dev_name, sizeof(cp.name));
> +	memcpy(cp.name, name, sizeof(cp.name));
>   
>   	return __hci_cmd_sync_status(hdev, HCI_OP_WRITE_LOCAL_NAME,
>   					    sizeof(cp), &cp,
> @@ -3471,7 +3471,7 @@ int hci_powered_update_sync(struct hci_dev *hdev)
>   			hci_write_fast_connectable_sync(hdev, false);
>   		hci_update_scan_sync(hdev);
>   		hci_update_class_sync(hdev);
> -		hci_update_name_sync(hdev);
> +		hci_update_name_sync(hdev, hdev->dev_name);
>   		hci_update_eir_sync(hdev);
>   	}
>   
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 46b22708dfbd2..da662e1823ae5 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -3876,8 +3876,11 @@ static void set_name_complete(struct hci_dev *hdev, void *data, int err)
>   
>   static int set_name_sync(struct hci_dev *hdev, void *data)
>   {
> +	struct mgmt_pending_cmd *cmd = data;
> +	struct mgmt_cp_set_local_name *cp = cmd->param;
> +
>   	if (lmp_bredr_capable(hdev)) {
> -		hci_update_name_sync(hdev);
> +		hci_update_name_sync(hdev, cp->name);
>   		hci_update_eir_sync(hdev);
>   	}
>   

Reviewed-by: Paul Menzel <pmenzel@...gen.mpg.de>


Kind regards,

Paul