[PATCH 3/3] i2c: i801: avoid panic if ioreamp fails

[Kefeng Wang <wangkefeng.wang@huawei.com>]

If ioremap fails, NULL pointer dereference will happen and
leading to a kernel panic when access the virtual address
in check_signature().

Fix it by check the return value of ioremap.

Cc: Jean Delvare <jdelvare@suse.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-i2c@vger.kernel.org
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 drivers/i2c/busses/i2c-i801.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 679c6c41f64b..fc6ccb8aba17 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1068,7 +1068,10 @@ static void __init input_apanel_init(void)
 	void __iomem *bios;
 	const void __iomem *p;
 
-	bios = ioremap(0xF0000, 0x10000); /* Can't fail */
+	bios = ioremap(0xF0000, 0x10000);
+	if (!base)
+		return -ENOMEM;
+
 	p = bios_signature(bios);
 	if (p) {
 		/* just use the first address */
-- 
2.20.1