Commit e6056b1f authored by Kean Ren's avatar Kean Ren Committed by Guenter Roeck
Browse files

hwmon: (lenovo-ec-sensors): Fix EC "MCHP" signature validation logic 



The EC signature check uses && instead of || between the four
byte comparisons.  With &&, the condition is true only when ALL
four bytes fail to match simultaneously, meaning the driver
accepts a device as a valid Microchip EC if ANY single byte of
the 4-byte "MCHP" signature happens to match.

Due to short-circuit evaluation, if the first byte reads back as
'M' (0x4D, a very common register value), the remaining three
comparisons are skipped entirely and the device is accepted.

Change && to || so the check rejects devices that do not fully
match the expected EC signature, as originally intended.

Fixes: 70118f85 ("hwmon: Add EC Chip driver for Lenovo ThinkStation motherboards")
Reviewed-by: default avatarMark Pearson <mpearson-lenovo@squebb.ca>
Signed-off-by: default avatarKean Ren <rh_king@163.com>
Link: https://lore.kernel.org/r/20260521035228.533317-3-rh_king@163.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 6c4e001c

drivers/hwmon/lenovo-ec-sensors.c

+3 −3
Original line number Diff line number Diff line
@@ -537,9 +537,9 @@ static int lenovo_ec_probe(struct platform_device *pdev) 
	outw_p(MCHP_SING_IDX, MCHP_EMI0_EC_ADDRESS);

	mutex_unlock(&ec_data->mec_mutex);



	if ((inb_p(MCHP_EMI0_EC_DATA_BYTE0) != 'M') &&

	    (inb_p(MCHP_EMI0_EC_DATA_BYTE1) != 'C') &&

	    (inb_p(MCHP_EMI0_EC_DATA_BYTE2) != 'H') &&

	if ((inb_p(MCHP_EMI0_EC_DATA_BYTE0) != 'M') ||

	    (inb_p(MCHP_EMI0_EC_DATA_BYTE1) != 'C') ||

	    (inb_p(MCHP_EMI0_EC_DATA_BYTE2) != 'H') ||

	    (inb_p(MCHP_EMI0_EC_DATA_BYTE3) != 'P'))

		return -ENODEV;