linux-kernel - Re: [PATCH 14/14] HID: i2c-hid: fix i2c_hid_get_raw

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Date:	Wed, 5 Dec 2012 11:40:02 +0100
From:	Benjamin Tissoires <benjamin.tissoires@...il.com>
To:	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Jean Delvare <khali@...ux-fr.org>, linux-input@...r.kernel.org,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/14] HID: i2c-hid: fix i2c_hid_get_raw_report count mismatches

Hi,

sorry, but when I re-read it, it seems that I missed a +2 in the call
of i2c_hid_get_report.

So Jean, Jiri, please ignore this one. I'm really sorry if you already
started reviewing it.

I'll send a v2 with the missing patches early this afternoon.

Cheers,
Benjamin

On Tue, Dec 4, 2012 at 4:27 PM, Benjamin Tissoires
<benjamin.tissoires@...il.com> wrote:
> The previous memcpy implementation relied on the size advertized by the
> device. There were no guarantees that buf was big enough.
>
> Some gymnastic is also required with the +2/-2 to take into account
> the first 2 bytes where the total length is supplied by the device.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
> ---
>  drivers/hid/i2c-hid/i2c-hid.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index 62988f1..de3566f 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -503,13 +503,14 @@ static int i2c_hid_get_raw_report(struct hid_device *hid,
>  {
>         struct i2c_client *client = hid->driver_data;
>         struct i2c_hid *ihid = i2c_get_clientdata(client);
> +       size_t rcount;
>         int ret;
>
>         if (report_type == HID_OUTPUT_REPORT)
>                 return -EINVAL;
>
> -       if (count > ihid->bufsize)
> -               count = ihid->bufsize;
> +       if (count > ihid->bufsize - 2)
> +               count = ihid->bufsize - 2;
>
>         ret = i2c_hid_get_report(client,
>                         report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
> @@ -518,7 +519,13 @@ static int i2c_hid_get_raw_report(struct hid_device *hid,
>         if (ret < 0)
>                 return ret;
>
> -       count = ihid->inbuf[0] | (ihid->inbuf[1] << 8);
> +       rcount = ihid->inbuf[0] | (ihid->inbuf[1] << 8);
> +
> +       if (!rcount)
> +               return 0;
> +
> +       if (count > rcount - 2)
> +               count = rcount - 2;
>
>         memcpy(buf, ihid->inbuf + 2, count);
>
> --
> 1.8.0.1
>
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