linux-kernel - Re: [PATCH next] HID: hid-goodix: Fix a signedness bug in goodix_hid_get_raw

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Message-ID: <5660b5ea-0806-493e-8364-15b0d519be76@stanley.mountain>
Date: Sat, 24 Aug 2024 00:32:53 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Charles Wang <charles.goodix@...il.com>, Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH next] HID: hid-goodix: Fix a signedness bug in
 goodix_hid_get_raw_report()

On Fri, Aug 23, 2024 at 01:10:49PM -0700, Dmitry Torokhov wrote:
> Hi Dan,
> 
> On Fri, Aug 23, 2024 at 03:51:27PM +0300, Dan Carpenter wrote:
> > GOODIX_HID_PKG_LEN_SIZE defined as sizeof(u16) (type size_t).  If the
> > goodix_hid_check_ack_status() function times out and return -EINVAL then,
> > because of type promotion, the negative error code is treated as a high
> > positive value which is success.
> > 
> > Fix this by adding an explicit check for negative error codes.
> > 
> > Fixes: 75e16c8ce283 ("HID: hid-goodix: Add Goodix HID-over-SPI driver")
> > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > ---
> >  drivers/hid/hid-goodix-spi.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hid/hid-goodix-spi.c b/drivers/hid/hid-goodix-spi.c
> > index 5103bf0aada4..59415f95c675 100644
> > --- a/drivers/hid/hid-goodix-spi.c
> > +++ b/drivers/hid/hid-goodix-spi.c
> > @@ -435,7 +435,8 @@ static int goodix_hid_get_raw_report(struct hid_device *hid,
> >  
> >  	/* Step2: check response data status */
> >  	response_data_len = goodix_hid_check_ack_status(ts);
> > -	if (response_data_len <= GOODIX_HID_PKG_LEN_SIZE)
> > +	if (response_data_len < 0 ||
> > +	    response_data_len <= GOODIX_HID_PKG_LEN_SIZE)
> >  		return -EINVAL;
> 
> I think this is too subtle and we may lose your fix again in
> restructuring/refactoring. Could you change goodix_hid_check_ack_status()
> to take length as an argument to be filled in? And then we'd do:
> 
> 	error = goodix_hid_check_ack_status(ts, &response_data_len);
> 	if (error)
> 		return error;
> 
> The check for the correct length of the response could go into
> goodix_hid_check_ack_status() as well.
> 
> What do you think?

I'm fine with this.

I bet that you already wrote the patch that your describing.  If you want to
just merge that and give me reported-by credit then that's fine by me.

I can also resend.  I don't mind doing that.  I've already written the patch
that you're describing and I just have to write the commit message and hit send.
I can send it on Monday.  Whatever is easiest.

regards,
dan carpenter