V4L/DVB: gspca - sonixj: Bad detection of the end of image

The 'end of image' block may be splitted between two ISOC packets.
This case was not tested, so, some images could be lost and concatenated
to previous one(s), raising 'frame overflow' errors.
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/sonixj.c

@@ -2820,38 +2820,52 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
 	struct sd *sd = (struct sd *) gspca_dev;
 	int sof, avg_lum;
 
-	sof = len - 64;
-	if (sof >= 0 && data[sof] == 0xff && data[sof + 1] == 0xd9) {
-
-		/* end of frame */
-		gspca_frame_add(gspca_dev, LAST_PACKET,
-				data, sof + 2);
-		if (sd->ag_cnt < 0)
-			return;
+	/* the image ends on a 64 bytes block starting with
+	 *	ff d9 ff ff 00 c4 c4 96
+	 * and followed by various information including luminosity */
+	/* this block may be splitted between two packets */
+	/* a new image always starts in a new packet */
+	switch (gspca_dev->last_packet_type) {
+	case DISCARD_PACKET:		/* restart image building */
+		sof = len - 64;
+		if (sof >= 0 && data[sof] == 0xff && data[sof + 1] == 0xd9)
+			gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);
+		return;
+	case LAST_PACKET:		/* put the JPEG 422 header */
+		gspca_frame_add(gspca_dev, FIRST_PACKET,
+				sd->jpeg_hdr, JPEG_HDR_SZ);
+		break;
+	}
+	gspca_frame_add(gspca_dev, INTER_PACKET, data, len);
+
+	data = gspca_dev->image;
+	if (data == NULL)
+		return;
+	sof = gspca_dev->image_len - 64;
+	if (data[sof] != 0xff
+	 || data[sof + 1] != 0xd9)
+		return;
+
+	/* end of image found - remove the trailing data */
+	gspca_dev->image_len = sof + 2;
+	gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);
+	if (sd->ag_cnt < 0)
+		return;
 /* w1 w2 w3 */
 /* w4 w5 w6 */
 /* w7 w8 */
 /* w4 */
-		avg_lum = ((data[sof + 29] << 8) | data[sof + 30]) >> 6;
+	avg_lum = ((data[sof + 29] << 8) | data[sof + 30]) >> 6;
 /* w6 */
-		avg_lum += ((data[sof + 33] << 8) | data[sof + 34]) >> 6;
+	avg_lum += ((data[sof + 33] << 8) | data[sof + 34]) >> 6;
 /* w2 */
-		avg_lum += ((data[sof + 25] << 8) | data[sof + 26]) >> 6;
+	avg_lum += ((data[sof + 25] << 8) | data[sof + 26]) >> 6;
 /* w8 */
-		avg_lum += ((data[sof + 37] << 8) | data[sof + 38]) >> 6;
+	avg_lum += ((data[sof + 37] << 8) | data[sof + 38]) >> 6;
 /* w5 */
-		avg_lum += ((data[sof + 31] << 8) | data[sof + 32]) >> 4;
-		avg_lum >>= 4;
-		atomic_set(&sd->avg_lum, avg_lum);
-		return;
-	}
-	if (gspca_dev->last_packet_type == LAST_PACKET) {
-
-		/* put the JPEG 422 header */
-		gspca_frame_add(gspca_dev, FIRST_PACKET,
-			sd->jpeg_hdr, JPEG_HDR_SZ);
-	}
-	gspca_frame_add(gspca_dev, INTER_PACKET, data, len);
+	avg_lum += ((data[sof + 31] << 8) | data[sof + 32]) >> 4;
+	avg_lum >>= 4;
+	atomic_set(&sd->avg_lum, avg_lum);
 }
 
 static int sd_setbrightness(struct gspca_dev *gspca_dev, __s32 val)