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

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Message-Id: <20181226030911.72845-1-kjlu@umn.edu>
Date:   Tue, 25 Dec 2018 21:09:11 -0600
From:   Kangjie Lu <kjlu@....edu>
To:     kjlu@....edu
Cc:     pakki001@....edu, Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] rtc: fix a missing check of block data read

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 <kjlu@....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)