From 32687886344b8740980b4d45f0b0b7b3bcd2599b Mon Sep 17 00:00:00 2001
From: Sean Young <sean@mess.org>
Date: Wed, 1 Feb 2017 20:08:56 -0200
Subject: [PATCH] UPSTREAM: [media] lirc: cannot read from tx-only device

Bail out early, otherwise we follow a null pointer.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
(cherry picked from commit 32002f725fc708dccc6263b19b56fa3d91626be1)
Signed-off-by: Ziyuan Xu <xzy.xu@rock-chips.com>
---
 drivers/media/rc/lirc_dev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
index 18b4daed8065..17d2723148b7 100644
--- a/drivers/media/rc/lirc_dev.c
+++ b/drivers/media/rc/lirc_dev.c
@@ -651,6 +651,9 @@ ssize_t lirc_dev_fop_read(struct file *file,
 		return -ENODEV;
 	}
 
+	if (!LIRC_CAN_REC(ir->d.features))
+		return -EINVAL;
+
 	dev_dbg(ir->d.dev, LOGHEAD "read called\n", ir->d.name, ir->d.minor);
 
 	buf = kzalloc(ir->chunk_size, GFP_KERNEL);