media: adv7842: Avoid possible out-of-bounds array accesses in adv7842_cp_log_status()

commit 8163419e3e05d71dcfa8fb49c8fdf8d76908fe51 upstream.

It's possible for cp_read() and hdmi_read() to return -EIO. Those
values are further used as indexes for accessing arrays.

Fix that by checking return values where it's needed.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: a89bcd4 ("[media] adv7842: add new video decoder driver")
Cc: stable@vger.kernel.org
Signed-off-by: Ivan Abramov <i.abramov@mt-integration.ru>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>

Author: Ivan Abramov

drivers/media/i2c/adv7842.c

@@ -2661,6 +2661,7 @@ static int adv7842_cp_log_status(struct v4l2_subdev *sd)
 	/* CP block */
 	struct adv7842_state *state = to_state(sd);
 	struct v4l2_dv_timings timings;
+	int temp;
 	u8 reg_io_0x02 = io_read(sd, 0x02);
 	u8 reg_io_0x21 = io_read(sd, 0x21);
 	u8 reg_rep_0x77 = rep_read(sd, 0x77);
@@ -2783,8 +2784,9 @@ static int adv7842_cp_log_status(struct v4l2_subdev *sd)
 		  (((reg_io_0x02 >> 2) & 0x01) ^ (reg_io_0x02 & 0x01)) ?
 			"(16-235)" : "(0-255)",
 		  (reg_io_0x02 & 0x08) ? "enabled" : "disabled");
+	temp = cp_read(sd, 0xf4) >> 4;
 	v4l2_info(sd, "Color space conversion: %s\n",
-		  csc_coeff_sel_rb[cp_read(sd, 0xf4) >> 4]);
+		  temp < 0 ? "" : csc_coeff_sel_rb[temp]);
 
 	if (!is_digital_input(sd))
 		return 0;
@@ -2814,8 +2816,9 @@ static int adv7842_cp_log_status(struct v4l2_subdev *sd)
 			hdmi_read(sd, 0x5f));
 	v4l2_info(sd, "AV Mute: %s\n",
 			(hdmi_read(sd, 0x04) & 0x40) ? "on" : "off");
+	temp = hdmi_read(sd, 0x0b) >> 6;
 	v4l2_info(sd, "Deep color mode: %s\n",
-			deep_color_mode_txt[hdmi_read(sd, 0x0b) >> 6]);
+			temp < 0 ? "" : deep_color_mode_txt[temp]);
 
 	adv7842_log_infoframes(sd);