usb: gadget: uvc: Fix ERR_PTR dereference in uvc_v4l2.c

commit a7bb96b18864225a694e3887ac2733159489e4b0 upstream.

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().

Signed-off-by: Abhishek Tamboli <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jianqi Ren <[email protected]>
Signed-off-by: He Zhe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Abhishek-Tamboli9

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)
@@ -265,7 +269,10 @@ uvc_v4l2_try_format(struct file *file, void *fh, struct v4l2_format *fmt)
 	fmt->fmt.pix.field = V4L2_FIELD_NONE;
 	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 PTR_ERR(fmtdesc);
+	fmt->fmt.pix.pixelformat = fmtdesc->fcc;
 	fmt->fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
 	fmt->fmt.pix.priv = 0;
 
@@ -375,6 +382,9 @@ 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 PTR_ERR(fmtdesc);
+
 	f->pixelformat = fmtdesc->fcc;
 
 	return 0;