[PATCH v2] Bluetooth: btnxpuart: Fix out-of-bounds firmware read in nxp_recv_fw_req_v3()

[PATCH v2] Bluetooth: btnxpuart: Fix out-of-bounds firmware read in nxp_recv_fw_req_v3()

[Maoyi Xie]

During the v3 firmware download the controller sends a v3_data_req with a
32 bit offset and a 16 bit len. nxp_recv_fw_req_v3() checks only the lower
bound of the offset and then sends firmware from that offset.

  nxpdev->fw_dnld_v3_offset = offset - nxpdev->fw_v3_offset_correction;
  serdev_device_write_buf(nxpdev->serdev, nxpdev->fw->data +
                          nxpdev->fw_dnld_v3_offset, len);

Nothing checks that fw_dnld_v3_offset + len stays within nxpdev->fw->size,
so a controller that asks for an offset or length past the firmware image
makes the driver read past the end of nxpdev->fw->data and send that
memory back over UART.

nxp_recv_fw_req_v1() already bounds the same write. Add the equivalent
check to the v3 path, reject the request when it falls outside the firmware
image, and zero len on the error path so the fw_v3_prev_sent bookkeeping at
free_skb stays consistent.

Fixes: 689ca16e5232 ("Bluetooth: NXP: Add protocol support for NXP Bluetooth chipsets")
Suggested-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Reviewed-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Cc: stable@vger.kernel.org
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
---
v2: rewrap the commit message under 75 columns and drop the hard tabs from
    the quoted code so checkpatch and gitlint pass. No code change, so I
    carried Neeraj's Reviewed-by from v1 (the diff is byte-identical).

The Suggested-by credits his suggestion to zero len on the reject path.

 drivers/bluetooth/btnxpuart.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
index e7036a48ce48..6a1cffe08d5f 100644
--- a/drivers/bluetooth/btnxpuart.c
+++ b/drivers/bluetooth/btnxpuart.c
@@ -1267,6 +1267,12 @@ static int nxp_recv_fw_req_v3(struct hci_dev *hdev, struct sk_buff *skb)
 	}
 
 	nxpdev->fw_dnld_v3_offset = offset - nxpdev->fw_v3_offset_correction;
+	if (nxpdev->fw_dnld_v3_offset >= nxpdev->fw->size ||
+	    len > nxpdev->fw->size - nxpdev->fw_dnld_v3_offset) {
+		bt_dev_err(hdev, "FW download out of bounds, ignoring request");
+		len = 0;
+		goto free_skb;
+	}
 	serdev_device_write_buf(nxpdev->serdev, nxpdev->fw->data +
 				nxpdev->fw_dnld_v3_offset, len);
 
-- 
2.34.1

Re: [PATCH v2] Bluetooth: btnxpuart: Fix out-of-bounds firmware read in nxp_recv_fw_req_v3()

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Wed, 17 Jun 2026 16:36:52 +0800 you wrote:
> During the v3 firmware download the controller sends a v3_data_req with a
> 32 bit offset and a 16 bit len. nxp_recv_fw_req_v3() checks only the lower
> bound of the offset and then sends firmware from that offset.
> 
>   nxpdev->fw_dnld_v3_offset = offset - nxpdev->fw_v3_offset_correction;
>   serdev_device_write_buf(nxpdev->serdev, nxpdev->fw->data +
>                           nxpdev->fw_dnld_v3_offset, len);
> 
> [...]

Here is the summary with links:
  - [v2] Bluetooth: btnxpuart: Fix out-of-bounds firmware read in nxp_recv_fw_req_v3()
    https://git.kernel.org/bluetooth/bluetooth-next/c/25c286d75821

You are awesome, thank you!
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