linux-kernel - Re: [PATCH v2] usb: gadget: uvc: Fix ERR_PTR dereference in uvc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <2024081508-swinger-arrange-02dd@gregkh>
Date: Thu, 15 Aug 2024 11:32:13 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Abhishek Tamboli <abhishektamboli9@...il.com>
Cc: dan.scally@...asonboard.com, laurent.pinchart@...asonboard.com,
	dan.carpenter@...aro.org, linux-usb@...r.kernel.org,
	skhan@...uxfoundation.org, rbmarliere@...il.com,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: gadget: uvc: Fix ERR_PTR dereference in
 uvc_v4l2.c

On Thu, Aug 15, 2024 at 02:49:36PM +0530, Abhishek Tamboli wrote:
> Hi Greg,
> Thank you for the feedback.
> 
> On Thu, Aug 15, 2024 at 10:00:27AM +0200, Greg KH wrote:
> > On Thu, Aug 15, 2024 at 12:44:16PM +0530, Abhishek Tamboli wrote:
> > > Fix potential dereferencing of ERR_PTR() in find_format_by_pix()
> > > and uvc_v4l2_enum_format().
> > > 
> > > Fix the following smatch errors:
> > > 
> > > drivers/usb/gadget/function/uvc_v4l2.c:124 find_format_by_pix()
> > > error: 'fmtdesc' dereferencing possible ERR_PTR()
> > > 
> > > drivers/usb/gadget/function/uvc_v4l2.c:392 uvc_v4l2_enum_format()
> > > error: 'fmtdesc' dereferencing possible ERR_PTR()
> > > 
> > > Also, fix similar issue in uvc_v4l2_try_format() for potential
> > > dereferencing of ERR_PTR().
> > > 
> > > Fixes: 588b9e85609b ("usb: gadget: uvc: add v4l2 enumeration api calls")
> > > Fixes: e219a712bc06 ("usb: gadget: uvc: add v4l2 try_format api call")
> > > Signed-off-by: Abhishek Tamboli <abhishektamboli9@...il.com>
> > > ---
> > > Changes in v2:
> > > - Add check for dereferencing of ERR_PTR() in uvc_v4l2_try_format()
> > > 
> > >  drivers/usb/gadget/function/uvc_v4l2.c | 12 +++++++++++-
> > >  1 file changed, 11 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c
> > > index a024aecb76dc..8bb88c864b60 100644
> > > --- a/drivers/usb/gadget/function/uvc_v4l2.c
> > > +++ b/drivers/usb/gadget/function/uvc_v4l2.c
> > > @@ -121,6 +121,9 @@ static struct uvcg_format *find_format_by_pix(struct uvc_device *uvc,
> > >  	list_for_each_entry(format, &uvc->header->formats, entry) {
> > >  		const struct uvc_format_desc *fmtdesc = to_uvc_format(format->fmt);
> > > 
> > > +		if (IS_ERR(fmtdesc))
> > > +			continue;
> > > +
> > >  		if (fmtdesc->fcc == pixelformat) {
> > >  			uformat = format->fmt;
> > >  			break;
> > > @@ -240,6 +243,7 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
> > >  	struct uvc_video *video = &uvc->video;
> > >  	struct uvcg_format *uformat;
> > >  	struct uvcg_frame *uframe;
> > > +	const struct uvc_format_desc *fmtdesc;
> > >  	u8 *fcc;
> > > 
> > >  	if (fmt->type != video->queue.queue.type)
> > > @@ -277,7 +281,10 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
> > >  		fmt->fmt.pix.height = uframe->frame.w_height;
> > >  		fmt->fmt.pix.bytesperline = uvc_v4l2_get_bytesperline(uformat, uframe);
> > >  		fmt->fmt.pix.sizeimage = uvc_get_frame_size(uformat, uframe);
> > > -		fmt->fmt.pix.pixelformat = to_uvc_format(uformat)->fcc;
> > > +		fmtdesc = to_uvc_format(uformat);
> > > +		if (IS_ERR(fmtdesc))
> > > +			return -EINVAL;
> > 
> > Why not return the error given to you?
> Returning -EINVAL directly was based on the current implementation of to_uvc_format(), 
> which only returns ERR_PTR(-EINVAL) in case of error.
> > 
> > > +		fmt->fmt.pix.pixelformat = fmtdesc->fcc;
> > >  	}
> > >  	fmt->fmt.pix.field = V4L2_FIELD_NONE;
> > >  	fmt->fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
> > > @@ -389,6 +396,9 @@ uvc_v4l2_enum_format(struct file *file, void *fh, struct v4l2_fmtdesc *f)
> > >  		return -EINVAL;
> > > 
> > >  	fmtdesc = to_uvc_format(uformat);
> > > +	if (IS_ERR(fmtdesc))
> > > +		return -EINVAL;
> > 
> > Same here.
> If you'd like me to make the changes to use PTR_ERR()? 

Yes please.