Re: [PATCH 1/1] HID: logitech-dj: Prevent REPORT_ID_DJ_SHORT related user initiated OOB write

[Benjamin Tissoires <bentiss@kernel.org>]

On Mar 17 2026, Lee Jones wrote:
> logi_dj_recv_send_report() assumes that all incoming REPORT_ID_DJ_SHORT
> reports are 14 Bytes (DJREPORT_SHORT_LENGTH - 1) long.  It uses that
> assumption to load the associated field's 'value' array with 14 Bytes of
> data.  However, if a malicious user only sends say 1 Byte of data,
> 'report_count' will be 1 and only 1 Byte of memory will be allocated to
> the 'value' Byte array.  When we come to populate 'value[1-13]' we will
> experience an OOB write.
> 
> Signed-off-by: Lee Jones <lee@kernel.org>
> ---
>  drivers/hid/hid-logitech-dj.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
> index 44b716697510..885b986c7a12 100644
> --- a/drivers/hid/hid-logitech-dj.c
> +++ b/drivers/hid/hid-logitech-dj.c
> @@ -1282,6 +1282,12 @@ static int logi_dj_recv_send_report(struct dj_receiver_dev *djrcv_dev,
>  		return -ENODEV;
>  	}
>  
> +	if (report->maxfield < 1 || report->field[0]->report_count != DJREPORT_SHORT_LENGTH - 1) {

This is all static information. So this should be checked in the
.probe(), once the device has been parsed, not for every single call of
logi_dj_recv_send_report().

Cheers,
Benjamin

> +		hid_err(hdev, "Expected size of dj report is %d, but got %d",
> +			DJREPORT_SHORT_LENGTH - 1, report->field[0]->report_count);
> +		return -EINVAL;
> +	}
> +
>  	for (i = 0; i < DJREPORT_SHORT_LENGTH - 1; i++)
>  		report->field[0]->value[i] = data[i];
>  
> -- 
> 2.53.0.851.ga537e3e6e9-goog
> 
>