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Date:   Mon, 8 Feb 2021 18:06:11 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Colin King <colin.king@canonical.com>
Cc:     Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Nestor Lopez Casado <nlopezcasad@logitech.com>,
        linux-input@vger.kernel.org, kernel-janitors@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] HID: logitech-dj: fix unintentional integer overflow on
 left shift
Message-ID: <20210208150610.GI2696@kadam>
References: <20210207232120.8885-1-colin.king@canonical.com>
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On Sun, Feb 07, 2021 at 11:21:20PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Shifting the integer value 1 is evaluated using 32-bit rithmetic
> and then used in an expression that expects a 64-bit value, so
> there is potentially an integer overflow. Fix this by using th
> BIT_ULL macro to perform the shift and avoid the overflow.
> 
> Addresses-Coverity: ("Uninitentional integer overflow")
> Fixes: 534a7b8e10ec ("HID: Add full support for Logitech Unifying receivers")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/hid/hid-logitech-dj.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
> index 45e7e0bdd382..747f41be0603 100644
> --- a/drivers/hid/hid-logitech-dj.c
> +++ b/drivers/hid/hid-logitech-dj.c
> @@ -1035,7 +1035,7 @@ static void logi_dj_recv_forward_null_report(struct dj_receiver_dev *djrcv_dev,
>  	memset(reportbuffer, 0, sizeof(reportbuffer));
>  
>  	for (i = 0; i < NUMBER_OF_HID_REPORTS; i++) {
                        ^^^^^^^^^^^^^^^^^^^^^
This is 32, so it can't be undefined.

> -		if (djdev->reports_supported & (1 << i)) {
> +		if (djdev->reports_supported & BIT_ULL(i)) {
>  			reportbuffer[0] = i;
>  			if (hid_input_report(djdev->hdev,
>  					     HID_INPUT_REPORT,

regards,
dan carpenter