From e6056b1f5a38bbe57ccbbba2609efecbd87ae08c Mon Sep 17 00:00:00 2001 From: Kean Ren Date: Thu, 21 May 2026 11:52:28 +0800 Subject: [PATCH] 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: 70118f85e6538 ("hwmon: Add EC Chip driver for Lenovo ThinkStation motherboards") Reviewed-by: Mark Pearson Signed-off-by: Kean Ren Link: https://lore.kernel.org/r/20260521035228.533317-3-rh_king@163.com Signed-off-by: Guenter Roeck --- drivers/hwmon/lenovo-ec-sensors.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/hwmon/lenovo-ec-sensors.c b/drivers/hwmon/lenovo-ec-sensors.c index a16cc5e4053a..24a182abf9a3 100644 --- a/drivers/hwmon/lenovo-ec-sensors.c +++ b/drivers/hwmon/lenovo-ec-sensors.c @@ -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;