From: Pan Bian <bianpan2016@163.com>
Date: Tue, 12 Nov 2019 17:04:54 -0800
Subject: Input: cyttsp4_core - fix use after free bug
Git-commit: 79aae6acbef16f720a7949f8fc6ac69816c79d62
Patch-mainline: 5.4-rc8
References: bnc#1151927 5.3.16

The device md->input is used after it is released. Setting the device
data to NULL is unnecessary as the device is never used again. Instead,
md->input should be assigned NULL to avoid accessing the freed memory
accidently. Besides, checking md->si against NULL is superfluous as it
points to a variable address, which cannot be NULL.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Link: https://lore.kernel.org/r/1572936379-6423-1-git-send-email-bianpan2016@163.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/input/touchscreen/cyttsp4_core.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/drivers/input/touchscreen/cyttsp4_core.c
+++ b/drivers/input/touchscreen/cyttsp4_core.c
@@ -1990,11 +1990,6 @@ static int cyttsp4_mt_probe(struct cytts
 
 	/* get sysinfo */
 	md->si = &cd->sysinfo;
-	if (!md->si) {
-		dev_err(dev, "%s: Fail get sysinfo pointer from core p=%p\n",
-			__func__, md->si);
-		goto error_get_sysinfo;
-	}
 
 	rc = cyttsp4_setup_input_device(cd);
 	if (rc)
@@ -2004,8 +1999,6 @@ static int cyttsp4_mt_probe(struct cytts
 
 error_init_input:
 	input_free_device(md->input);
-error_get_sysinfo:
-	input_set_drvdata(md->input, NULL);
 error_alloc_failed:
 	dev_err(dev, "%s failed.\n", __func__);
 	return rc;