[PATCH v3 2/2] hwmon: (lenovo-ec-sensors): Fix EC "MCHP" signature validation logic

[Kean Ren]

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.

Reviewed-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
Signed-off-by: Kean Ren <rh_king@xxxxxxx>
---
Changes in v3: Corrected bug description and regenerated.

 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;
 
-- 
2.53.0