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[109.173.93.221]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5944a3a1a71sm4133906e87.83.2025.11.10.07.22.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Nov 2025 07:22:44 -0800 (PST) From: Alexandr Sapozhnikov To: =?UTF-8?q?Pali=20Roh=C3=A1r?= , Jean Delvare , Guenter Roeck Cc: Alexandr Sapozhnikov , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] hwmon: (dell-smm) overflow check during multiplication Date: Mon, 10 Nov 2025 18:22:41 +0300 Message-ID: <20251110152242.26-1-alsp705@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Added overflow checking when multiplying int by int and writing the result to long to prevent data corruption due to overflow. Fixes: b1986c8e31a3 ("hwmon: (dell-smm) Add support for fanX_min, fanX_max and fanX_target") Signed-off-by: Alexandr Sapozhnikov --- drivers/hwmon/dell-smm-hwmon.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c index 1572b5416015..ee2fe651c07f 100644 --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -34,6 +34,7 @@ #include #include #include +#include #include @@ -736,6 +737,11 @@ static umode_t dell_smm_is_visible(const void *drvdata, enum hwmon_sensor_types return 0; } +static int dell_smm_check_overflow(int a, int b) +{ + return (long long)a * (long long)b > LONG_MAX; +} + static int dell_smm_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val) { @@ -769,12 +775,17 @@ static int dell_smm_read(struct device *dev, enum hwmon_sensor_types type, u32 a return 0; case hwmon_fan_min: + if (dell_smm_check_overflow(data->fan_nominal_speed[channel][0], mult) + return -EINVAL; *val = data->fan_nominal_speed[channel][0] * mult; return 0; case hwmon_fan_max: + if (dell_smm_check_overflow( + data->fan_nominal_speed[channel][data->i8k_fan_max], mult) + return -EINVAL; *val = data->fan_nominal_speed[channel][data->i8k_fan_max] * mult; - + return 0; case hwmon_fan_target: ret = i8k_get_fan_status(data, channel); @@ -784,6 +795,8 @@ static int dell_smm_read(struct device *dev, enum hwmon_sensor_types type, u32 a if (ret > data->i8k_fan_max) ret = data->i8k_fan_max; + if (dell_smm_check_overflow(data->fan_nominal_speed[channel][ret], mult) + return -EINVAL; *val = data->fan_nominal_speed[channel][ret] * mult; return 0; -- 2.51.0