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hwmon: (aspeed-g6-pwm-tach) Guard fan RPM calculation against divide-by-zero

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Sashiko reports:

In the aspeed-g6-pwm-tacho driver, the aspeed_tach_val_to_rpm() function
calculates the fan RPM using the tachometer value. However, it does not
check if the tachometer value is zero before performing the division.

If the hardware reports a tachometer value of 0 (which can happen due to
an extremely fast pulse, a stuck edge, or a hardware glitch), the
calculated tach_div evaluates to 0. The subsequent call to do_div() with
tach_div as the divisor triggers a divide-by-zero exception, leading to
a kernel panic.

Check the divisor against zero to fix the problem.

Fixes: 7e1449cd15 ("hwmon: (aspeed-g6-pwm-tacho): Support for ASPEED g6 PWM/Fan tach")
Cc: Billy Tsai <billy_tsai@aspeedtech.com>
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Guenter Roeck 2026-06-29 16:18:18 -07:00
parent 9ef7dacd44
commit fe87b8dc67
1 changed files with 4 additions and 1 deletions
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5
drivers/hwmon/aspeed-g6-pwm-tach.c
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@ -293,7 +293,10 @@ static int aspeed_tach_val_to_rpm(struct aspeed_pwm_tach_data *priv, u32 tach_va
priv->clk_rate, tach_val, tach_div);
rpm = (u64)priv->clk_rate * 60;
do_div(rpm, tach_div);
if (tach_div)
do_div(rpm, tach_div);
else
rpm = 0;
return (int)rpm;
}