[PATCH v2] usb: gadget: uvc: Fix ERR_PTR dereference in uvc_v4l2.c

[Abhishek Tamboli <abhishektamboli9@gmail.com>]

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@gmail.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;
+		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;
+
 	f->pixelformat = fmtdesc->fcc;

 	return 0;
--
2.34.1