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| author |   Alexandre Mergnat <amergnat@baylibre.com> | 2025-04-28 12:06:48 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-10 07:17:09 -0400 |
| commit | cea549ca705b3c0c657f5ef62e7926ad7e8ca342 (patch) | |
| tree | 6941adad0bab0584c3697fb54a3c6efe459a031f | |
| parent | rtc: Make rtc_time64_to_tm() support dates before 1970 (diff) | |
| download | laptop-kernel-cea549ca705b3c0c657f5ef62e7926ad7e8ca342.tar.xz laptop-kernel-cea549ca705b3c0c657f5ef62e7926ad7e8ca342.zip | |
rtc: Fix offset calculation for .start_secs < 0
commit fe9f5f96cfe8b82d0f24cbfa93718925560f4f8d upstream.
The comparison
rtc->start_secs > rtc->range_max
has a signed left-hand side and an unsigned right-hand side.
So the comparison might become true for negative start_secs which is
interpreted as a (possibly very large) positive value.
As a negative value can never be bigger than an unsigned value
the correct representation of the (mathematical) comparison
rtc->start_secs > rtc->range_max
in C is:
rtc->start_secs >= 0 && rtc->start_secs > rtc->range_max
Use that to fix the offset calculation currently used in the
rtc-mt6397 driver.
Fixes: 989515647e783 ("rtc: Add one offset seconds to expand RTC range")
Signed-off-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250428-enable-rtc-v4-2-2b2f7e3f9349@baylibre.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/rtc/class.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index b88cd4fb295b..b1a2be1f9e3b 100644 --- a/drivers/rtc/class.c +++ b/drivers/rtc/class.c @@ -326,7 +326,7 @@ static void rtc_device_get_offset(struct rtc_device *rtc) * * Otherwise the offset seconds should be 0. */ - if (rtc->start_secs > rtc->range_max || + if ((rtc->start_secs >= 0 && rtc->start_secs > rtc->range_max) || rtc->start_secs + range_secs - 1 < rtc->range_min) rtc->offset_secs = rtc->start_secs - rtc->range_min; else if (rtc->start_secs > rtc->range_min) |