From: Colin Ian King Date: Tue, 5 Feb 2019 18:04:49 +0000 (+0000) Subject: rtc: ds1672: fix unintended sign extension X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=f0c04c276739ed8acbb41b4868e942a55b128dca;p=openwrt%2Fstaging%2Fblogic.git rtc: ds1672: fix unintended sign extension Shifting a u8 by 24 will cause the value to be promoted to an integer. If the top bit of the u8 is set then the following conversion to an unsigned long will sign extend the value causing the upper 32 bits to be set in the result. Fix this by casting the u8 value to an unsigned long before the shift. Detected by CoverityScan, CID#138801 ("Unintended sign extension") Fixes: edf1aaa31fc5 ("[PATCH] RTC subsystem: DS1672 driver") Signed-off-by: Colin Ian King Signed-off-by: Alexandre Belloni --- diff --git a/drivers/rtc/rtc-ds1672.c b/drivers/rtc/rtc-ds1672.c index 9caaccccaa57..b1ebca099b0d 100644 --- a/drivers/rtc/rtc-ds1672.c +++ b/drivers/rtc/rtc-ds1672.c @@ -58,7 +58,8 @@ static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm) "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", __func__, buf[0], buf[1], buf[2], buf[3]); - time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0]; + time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | + (buf[1] << 8) | buf[0]; rtc_time_to_tm(time, tm);