diff options
| author | Colin Ian King <colin.king@canonical.com> | 2018-02-15 19:36:14 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-25 16:13:15 +0200 |
| commit | 0c60045656488690b047aa535bc3c3328a544062 (patch) | |
| tree | ed4f0448eda94305dec95ad008266aa2317a4503 | |
| parent | dd6b3e0a66592a72914be1d38ba29f93804e3161 (diff) | |
rtc: tx4939: avoid unintended sign extension on a 24 bit shift
[ Upstream commit 347876ad47b9923ce26e686173bbf46581802ffa ]
The shifting of buf[5] by 24 bits to the left will be promoted to
a 32 bit signed int and then sign-extended to an unsigned long. If
the top bit of buf[5] is set then all then all the upper bits sec
end up as also being set because of the sign-extension. Fix this by
casting buf[5] to an unsigned long before the shift.
Detected by CoverityScan, CID#1465292 ("Unintended sign extension")
Fixes: 0e1492330cd2 ("rtc: add rtc-tx4939 driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/rtc/rtc-tx4939.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-tx4939.c b/drivers/rtc/rtc-tx4939.c index 560d9a5e0225..a9528083061d 100644 --- a/drivers/rtc/rtc-tx4939.c +++ b/drivers/rtc/rtc-tx4939.c @@ -86,7 +86,8 @@ static int tx4939_rtc_read_time(struct device *dev, struct rtc_time *tm) for (i = 2; i < 6; i++) buf[i] = __raw_readl(&rtcreg->dat); spin_unlock_irq(&pdata->lock); - sec = (buf[5] << 24) | (buf[4] << 16) | (buf[3] << 8) | buf[2]; + sec = ((unsigned long)buf[5] << 24) | (buf[4] << 16) | + (buf[3] << 8) | buf[2]; rtc_time_to_tm(sec, tm); return rtc_valid_tm(tm); } @@ -147,7 +148,8 @@ static int tx4939_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) alrm->enabled = (ctl & TX4939_RTCCTL_ALME) ? 1 : 0; alrm->pending = (ctl & TX4939_RTCCTL_ALMD) ? 1 : 0; spin_unlock_irq(&pdata->lock); - sec = (buf[5] << 24) | (buf[4] << 16) | (buf[3] << 8) | buf[2]; + sec = ((unsigned long)buf[5] << 24) | (buf[4] << 16) | + (buf[3] << 8) | buf[2]; rtc_time_to_tm(sec, &alrm->time); return rtc_valid_tm(&alrm->time); } |