linux-kernel - [PATCH] hwmon: (ltc2991) re-order conditions to fix off by one bug

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Message-ID: <Zoa9Y_UMY4_ROfhF@stanley.mountain>
Date: Thu, 4 Jul 2024 10:18:59 -0500
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>
Cc: Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>,
	linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH] hwmon: (ltc2991) re-order conditions to fix off by one bug

LTC2991_T_INT_CH_NR is 4.  The st->temp_en[] array has LTC2991_MAX_CHANNEL
(4) elements.  Thus if "channel" is equal to LTC2991_T_INT_CH_NR then we
have read one element beyond the end of the array.  Flip the conditions
around so that we check if "channel" is valid before using it as an array
index.

Fixes: 2b9ea4262ae9 ("hwmon: Add driver for ltc2991")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 drivers/hwmon/ltc2991.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/ltc2991.c b/drivers/hwmon/ltc2991.c
index a01f887392f9..573cd8f5721b 100644
--- a/drivers/hwmon/ltc2991.c
+++ b/drivers/hwmon/ltc2991.c
@@ -225,8 +225,8 @@ static umode_t ltc2991_is_visible(const void *data,
 	case hwmon_temp:
 		switch (attr) {
 		case hwmon_temp_input:
-			if (st->temp_en[channel] ||
-			    channel == LTC2991_T_INT_CH_NR)
+			if (channel == LTC2991_T_INT_CH_NR ||
+			    st->temp_en[channel])
 				return 0444;
 			break;
 		}
-- 
2.43.0