[PATCH] rtc: fix a missing check of block data read

[Kangjie Lu]

When i2c_smbus_read_i2c_block_data() fails, the read data in "buf" could
be incorrect and should not be used. The fix checks if
i2c_smbus_read_i2c_block_data fails, and if so, return its error code
upstream.

Signed-off-by: Kangjie Lu <k...@umn.edu>
---
 drivers/rtc/rtc-hym8563.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/rtc/rtc-hym8563.c b/drivers/rtc/rtc-hym8563.c
index e5ad527cb75e..d03f5d212eea 100644
--- a/drivers/rtc/rtc-hym8563.c
+++ b/drivers/rtc/rtc-hym8563.c
@@ -109,6 +109,8 @@ static int hym8563_rtc_read_time(struct device *dev, struct 
rtc_time *tm)
        }
 
        ret = i2c_smbus_read_i2c_block_data(client, HYM8563_SEC, 7, buf);
+       if (ret < 0)
+               return ret;
 
        tm->tm_sec = bcd2bin(buf[0] & HYM8563_SEC_MASK);
        tm->tm_min = bcd2bin(buf[1] & HYM8563_MIN_MASK);
-- 
2.17.2 (Apple Git-113)