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[85.146.143.223]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c21233a12e6sm32475466b.12.2026.08.13.14.20.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Aug 2026 14:20:28 -0700 (PDT) From: Mark Sercombe To: linux@roeck-us.net Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Sercombe Subject: [PATCH] hwmon: (w83627hf) fix out of bounds read of PWM register array Date: Thu, 13 Aug 2026 23:19:50 +0200 Message-ID: <20260813211950.535148-1-sercombe.joel.mark@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit w83627hf_update_device() reads PWM registers in a loop bounded by a hard coded "i <= 2", i.e. three iterations, for every chip type. For the W83627HF, W836X7HF_REG_PWM() indexes regpwm_627hf[], which only has two entries. The third iteration therefore reads regpwm_627hf[2], one element past the end of the array, and issues a read of a non existent PWM register. The W83627HF has only two PWM outputs (datasheet registers CR5A and CR5B, corresponding to W83627HF_REG_PWM1/PWM2) it has no third PWM register, and the driver correctly does not expose pwm3 for this chip. The function already computes num_pwms for this purpose, but the loop did not use it, and num_pwms itself did not account for the W83627HF having two PWMs. Include the W83627HF in the two PWM case and bound the loop by num_pwms so each chip only reads the PWM registers it actually has. Found by smatch. Compile tested only, I do not have the hardware. Signed-off-by: Mark Sercombe --- drivers/hwmon/w83627hf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/w83627hf.c b/drivers/hwmon/w83627hf.c index bb993bb09f40..e2cb7e8aeae3 100644 --- a/drivers/hwmon/w83627hf.c +++ b/drivers/hwmon/w83627hf.c @@ -478,7 +478,7 @@ static struct w83627hf_data *w83627hf_update_device(struct device *dev) { struct w83627hf_data *data = dev_get_drvdata(dev); int i, num_temps = (data->type == w83697hf) ? 2 : 3; - int num_pwms = (data->type == w83697hf) ? 2 : 3; + int num_pwms = (data->type == w83627hf || data->type == w83697hf) ? 2 : 3; mutex_lock(&data->update_lock); @@ -506,7 +506,7 @@ static struct w83627hf_data *w83627hf_update_device(struct device *dev) w83627hf_read_value(data, W83627HF_REG_FAN_MIN(i)); } - for (i = 0; i <= 2; i++) { + for (i = 0; i < num_pwms; i++) { u8 tmp = w83627hf_read_value(data, W836X7HF_REG_PWM(data->type, i)); /* bits 0-3 are reserved in 627THF */ -- 2.55.0