Re: [PATCH] Bluetooth: bfusb: Fix buffer over-read in rx processing loop

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Oct 07, 2025 at 07:29:42PM -0400, pip-izony wrote:
> From: Seungjin Bae <eeodqql09@gmail.com>
> 
> The bfusb_rx_complete() function parses incoming URB data in while loop.
> The logic does not sufficiently validate the remaining buffer size(count)
> accross loop iterations, which can lead to a buffer over-read.
> 
> For example, with 4-bytes remaining buffer, if the first iteration takes
> the `hdr & 0x4000` branch, 2-bytes are consumed. On the next iteration,
> only 2-bytes remain, but the else branch is trying to access the third
> byte(buf[2]). This causes an out-of-bounds read and a potential kernel panic.
> 
> This patch fixes the vulnerability by adding checks to ensure enough
> data remains in the buffer before it is accessed.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Seungjin Bae <eeodqql09@gmail.com>
> ---
>  drivers/bluetooth/bfusb.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/bluetooth/bfusb.c b/drivers/bluetooth/bfusb.c
> index 8df310983bf6..f17eae6dbd7d 100644
> --- a/drivers/bluetooth/bfusb.c
> +++ b/drivers/bluetooth/bfusb.c
> @@ -360,6 +360,10 @@ static void bfusb_rx_complete(struct urb *urb)
>  			count -= 2;
>  			buf   += 2;
>  		} else {
> +            if (count < 3) {
> +                bf_dev_err(data->hdev, "block header is too short");
> +                break;
> +            }
>  			len = (buf[2] == 0) ? 256 : buf[2];
>  			count -= 3;
>  			buf   += 3;
> -- 
> 2.43.0
> 
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>