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Commit 4fccd4a1 authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (g762) Fix overflows and crash seen when writing limit attributes 



Fix overflows seen when writing into fan speed limit attributes.
Also fix crash due to division by zero, seen when certain very
large values (such as 2147483648, or 0x80000000) are written
into fan speed limit attributes.

Fixes: 594fbe71 ("Add support for GMT G762/G763 PWM fan controllers")
Cc: Arnaud Ebalard <arno@natisbad.org>
Reviewed-by: default avatarJean Delvare <jdelvare@suse.de>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 59715f4d

drivers/hwmon/g762.c

+7 −4
Original line number Diff line number Diff line
@@ -193,14 +193,17 @@ static inline unsigned int rpm_from_cnt(u8 cnt, u32 clk_freq, u16 p, 
 * Convert fan RPM value from sysfs into count value for fan controller

 * register (FAN_SET_CNT).

 */

static inline unsigned char cnt_from_rpm(u32 rpm, u32 clk_freq, u16 p,

static inline unsigned char cnt_from_rpm(unsigned long rpm, u32 clk_freq, u16 p,

					 u8 clk_div, u8 gear_mult)

{

	unsigned long f1 = clk_freq * 30 * gear_mult;

	unsigned long f2 = p * clk_div;



	if (!rpm)	/* to stop the fan, set cnt to 255 */

		return 0xff;



	return clamp_val(((clk_freq * 30 * gear_mult) / (rpm * p * clk_div)),

			 0, 255);

	rpm = clamp_val(rpm, f1 / (255 * f2), ULONG_MAX / f2);

	return DIV_ROUND_CLOSEST(f1, rpm * f2);

}



/* helper to grab and cache data, at most one time per second */