From e651f2fae33634175fae956d896277cf916f5d09 Mon Sep 17 00:00:00 2001 From: Martin Blumenstingl Date: Sun, 25 Feb 2024 16:13:35 +0100 Subject: [PATCH] clocksource/drivers/arm_global_timer: Guard against division by zero 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 Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240225151336.2728533-3-martin.blumenstingl@googlemail.com --- 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 fd39cfabe526..4726a15b0afc 100644 --- a/drivers/clocksource/arm_global_timer.c +++ b/drivers/clocksource/arm_global_timer.c @@ -291,18 +291,17 @@ 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; /*