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Message-ID: <572c2a33-18dd-4bf0-8c41-e051d75f481b@molgen.mpg.de>
Date: Thu, 9 Oct 2025 09:01:18 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Seungjin Bae <eeodqql09@...il.com>
Cc: Marcel Holtmann <marcel@...tmann.org>,
Kyungtae Kim <Kyungtae.Kim@...tmouth.edu>,
Luiz Augusto von Dentz <luiz.dentz@...il.com>, linux-kernel@...r.kernel.org,
linux-bluetooth@...r.kernel.org
Subject: Re: [PATCH v3] Bluetooth: bfusb: Fix buffer over-read in rx
processing loop
Dear Seungjin,
Thank you for the patch.
Am 09.10.25 um 04:57 schrieb pip-izony:
> From: Seungjin Bae <eeodqql09@...il.com>
>
> The bfusb_rx_complete() function parses incoming URB data in a while loop.
> The logic does not sufficiently validate the remaining buffer size(count)
> across 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@...il.com>
> ---
> v1 -> v2: Fixing the error function name
> v2 -> v3: Addressing feedback from Paul Menzel
>
> drivers/bluetooth/bfusb.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/bluetooth/bfusb.c b/drivers/bluetooth/bfusb.c
> index 8df310983bf6..90ca5ab2acc3 100644
> --- a/drivers/bluetooth/bfusb.c
> +++ b/drivers/bluetooth/bfusb.c
> @@ -360,6 +360,12 @@ static void bfusb_rx_complete(struct urb *urb)
> count -= 2;
> buf += 2;
> } else {
> + if (count < 3) {
> + bt_dev_err(data->hdev,
> + "block header is too short (count=%d, expected=3)",
Why not: block header count %d < 3 (too short)
> + count);
> + break;
> + }
> len = (buf[2] == 0) ? 256 : buf[2];
> count -= 3;
> buf += 3;
Either way:
Reviewed-by: Paul Menzel <pmenzel@...gen.mpg.de>
Kind regards,
Paul
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