5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> [ Upstream commit e651f2fae33634175fae956d896277cf916f5d09 ] The result of the division of new_rate by gt_target_rate can be zero (if new_rate is smaller than gt_target_rate). Using that result as divisor without checking can result in a division by zero error. Guard against this by checking for a zero value earlier. While here, also change the psv variable to an unsigned long to make sure we don't overflow the datatype as all other types involved are also unsiged long. Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240225151336.2728533-3-martin.blumenstingl@xxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/clocksource/arm_global_timer.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c index e1c773bb55359..22a58d35a41fa 100644 --- a/drivers/clocksource/arm_global_timer.c +++ b/drivers/clocksource/arm_global_timer.c @@ -290,18 +290,17 @@ static int gt_clk_rate_change_cb(struct notifier_block *nb, switch (event) { case PRE_RATE_CHANGE: { - int psv; + unsigned long psv; - psv = DIV_ROUND_CLOSEST(ndata->new_rate, - gt_target_rate); - - if (abs(gt_target_rate - (ndata->new_rate / psv)) > MAX_F_ERR) + psv = DIV_ROUND_CLOSEST(ndata->new_rate, gt_target_rate); + if (!psv || + abs(gt_target_rate - (ndata->new_rate / psv)) > MAX_F_ERR) return NOTIFY_BAD; psv--; /* prescaler within legal range? */ - if (psv < 0 || psv > GT_CONTROL_PRESCALER_MAX) + if (psv > GT_CONTROL_PRESCALER_MAX) return NOTIFY_BAD; /* -- 2.43.0
