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clocksource/drivers/arm_global_timer: Guard against division by zero

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[ Upstream commit e651f2fae3 ]

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@googlemail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240225151336.2728533-3-martin.blumenstingl@googlemail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Martin Blumenstingl 2024-02-25 16:13:35 +01:00 committed by Greg Kroah-Hartman
parent 533893c2e0
commit 6d4fbad0ef
1 changed files with 5 additions and 6 deletions
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11
drivers/clocksource/arm_global_timer.c
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@ -290,18 +290,17 @@ static int gt_clk_rate_change_cb(struct notifier_block *nb,
switch (event) { switch (event) {
case PRE_RATE_CHANGE: case PRE_RATE_CHANGE:
{ {
int psv; unsigned long psv;
psv = DIV_ROUND_CLOSEST(ndata->new_rate, psv = DIV_ROUND_CLOSEST(ndata->new_rate, gt_target_rate);
gt_target_rate); if (!psv ||
abs(gt_target_rate - (ndata->new_rate / psv)) > MAX_F_ERR)
if (abs(gt_target_rate - (ndata->new_rate / psv)) > MAX_F_ERR)
return NOTIFY_BAD; return NOTIFY_BAD;
psv--; psv--;
/* prescaler within legal range? */ /* prescaler within legal range? */
if (psv < 0 || psv > GT_CONTROL_PRESCALER_MAX) if (psv > GT_CONTROL_PRESCALER_MAX)
return NOTIFY_BAD; return NOTIFY_BAD;
/* /*