[PATCH] Bluetooth: bcm203x: Fix use-after-free and memory leak in device lifecycle

[PATCH] Bluetooth: bcm203x: Fix use-after-free and memory leak in device lifecycle

[Salah Triki]

The driver stores a reference to the `usb_device` structure (`udev`)
in its private data (`data->udev`), which can persist beyond the
immediate context of the `bcm203x_probe()` function.

Without proper reference count management, this can lead to two issues:

1. A `use-after-free` scenario if `udev` is accessed after its main
   reference count drops to zero (e.g., if the device is disconnected
   and the `data` structure is still active).
2. A `memory leak` if `udev`'s reference count is not properly
   decremented during driver disconnect, preventing the `usb_device`
   object from being freed.

To correctly manage the `udev` lifetime, explicitly increment its
reference count with `usb_get_dev(udev)` when storing it in the
driver's private data. Correspondingly, decrement the reference count
with `usb_put_dev(data->udev)` in the `bcm203x_disconnect()` callback.

This ensures `udev` remains valid while referenced by the driver's
private data and is properly released when no longer needed.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
 drivers/bluetooth/bcm203x.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/bcm203x.c b/drivers/bluetooth/bcm203x.c
index c738ad0408cb..c91eaba33905 100644
--- a/drivers/bluetooth/bcm203x.c
+++ b/drivers/bluetooth/bcm203x.c
@@ -165,7 +165,7 @@ static int bcm203x_probe(struct usb_interface *intf, const struct usb_device_id
 	if (!data)
 		return -ENOMEM;
 
-	data->udev  = udev;
+	data->udev  = usb_get_dev(udev);
 	data->state = BCM203X_LOAD_MINIDRV;
 
 	data->urb = usb_alloc_urb(0, GFP_KERNEL);
@@ -243,6 +243,8 @@ static void bcm203x_disconnect(struct usb_interface *intf)
 
 	usb_set_intfdata(intf, NULL);
 
+	usb_put_dev(data->udev);
+
 	usb_free_urb(data->urb);
 	kfree(data->fw_data);
 	kfree(data->buffer);
-- 
2.43.0

Re: [PATCH] Bluetooth: bcm203x: Fix use-after-free and memory leak in device lifecycle

[Paul Menzel]

Dear Salah,


Thank you for your patch.


Am 26.07.25 um 08:23 schrieb Salah Triki:
> The driver stores a reference to the `usb_device` structure (`udev`)
> in its private data (`data->udev`), which can persist beyond the
> immediate context of the `bcm203x_probe()` function.
> 
> Without proper reference count management, this can lead to two issues:
> 
> 1. A `use-after-free` scenario if `udev` is accessed after its main
>     reference count drops to zero (e.g., if the device is disconnected
>     and the `data` structure is still active).
> 2. A `memory leak` if `udev`'s reference count is not properly
>     decremented during driver disconnect, preventing the `usb_device`
>     object from being freed.
> 
> To correctly manage the `udev` lifetime, explicitly increment its
> reference count with `usb_get_dev(udev)` when storing it in the
> driver's private data. Correspondingly, decrement the reference count
> with `usb_put_dev(data->udev)` in the `bcm203x_disconnect()` callback.
> 
> This ensures `udev` remains valid while referenced by the driver's
> private data and is properly released when no longer needed.
> 

Please add a Fixes: tag.

> Signed-off-by: Salah Triki <salah.triki@gmail.com>
> ---
>   drivers/bluetooth/bcm203x.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bluetooth/bcm203x.c b/drivers/bluetooth/bcm203x.c
> index c738ad0408cb..c91eaba33905 100644
> --- a/drivers/bluetooth/bcm203x.c
> +++ b/drivers/bluetooth/bcm203x.c
> @@ -165,7 +165,7 @@ static int bcm203x_probe(struct usb_interface *intf, const struct usb_device_id
>   	if (!data)
>   		return -ENOMEM;
>   
> -	data->udev  = udev;
> +	data->udev  = usb_get_dev(udev);
>   	data->state = BCM203X_LOAD_MINIDRV;
>   
>   	data->urb = usb_alloc_urb(0, GFP_KERNEL);
> @@ -243,6 +243,8 @@ static void bcm203x_disconnect(struct usb_interface *intf)
>   
>   	usb_set_intfdata(intf, NULL);
>   
> +	usb_put_dev(data->udev);
> +
>   	usb_free_urb(data->urb);
>   	kfree(data->fw_data);
>   	kfree(data->buffer);

The diff looks good to me, though other Bluetooth drivers seem to use 
`interface_to_usbdev(intf)`.


Kind regards,

Paul