From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51BCC41791F; Sat, 28 Feb 2026 17:45:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300724; cv=none; b=CgP9hgAThVpFQlgHqbWRg/L0QFPhrlulKYZPfIwxmICwX1EJPieyXgoyfPO2Ifxp+LyDlxmafcN2ZcRdPqHYvd/L/XSUgm7PgkybJuV4ReYYNiDPQlE3YG6+Bw2It6tPo3VpfNTYxEwL4FgOaq32UinK3ObsTDzXIYgU63kj1Co= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300724; c=relaxed/simple; bh=qoKGMMA8c2XybmlNisuifTOpQXuhT19rXE7/Qukienc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QqQy9Q9H7UhKFA8XU7aye912qes7hVJ6KybVCho2KFMpRU+626EeThli/CjngkXBn3wmx6UHPfSsRXT7PxpKBE8Lo9HX65wIysZTUCAQvKXNEo+wd74TJlFvR+X/xFrxV8F9/1/1gNBgbbEBlWo6ghUQqUPJNoAYshLyoLdMuJM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=e5aD8a2c; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="e5aD8a2c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63D95C116D0; Sat, 28 Feb 2026 17:45:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772300724; bh=qoKGMMA8c2XybmlNisuifTOpQXuhT19rXE7/Qukienc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e5aD8a2c3MfdrB2AdnWXGys4z2b0NG6xOY7BtP6FzsBu7sAJkMDl7+3/wdl1crnOc 2kbLjOALTqsWiFLhkHFHiRTcr33NdQ21o0I7/Hwtb/CKeEMH18esLsfv1LQMLDv5KL /5cI/oW7P940ma8pIEqO0tOKBcv190B9+he/b3Jogeu5G4HX2jUSawzPFwnvTT8cbR Xk/ciM8Imv8EIpmkdYs2/LIo/OC+J1IzF0MlKjeVH+Dc04b4dxFz8Q+l4SsPwzOIer YPCIdQwG4jPK2/YPkR8tQo+w6k0PzlB5sAV52Gq3/b3NMqT3w8syasAy4OfgPnZDqj PFNbW/h3plKEQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Gui-Dong Han , Ben Hutchings , Guenter Roeck , Sasha Levin Subject: [PATCH 6.19 760/844] hwmon: (max16065) Use READ/WRITE_ONCE to avoid compiler optimization induced race Date: Sat, 28 Feb 2026 12:31:13 -0500 Message-ID: <20260228173244.1509663-761-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228173244.1509663-1-sashal@kernel.org> References: <20260228173244.1509663-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Gui-Dong Han [ Upstream commit 007be4327e443d79c9dd9e56dc16c36f6395d208 ] Simply copying shared data to a local variable cannot prevent data races. The compiler is allowed to optimize away the local copy and re-read the shared memory, causing a Time-of-Check Time-of-Use (TOCTOU) issue if the data changes between the check and the usage. To enforce the use of the local variable, use READ_ONCE() when reading the shared data and WRITE_ONCE() when updating it. Apply these macros to the three identified locations (curr_sense, adc, and fault) where local variables are used for error validation, ensuring the value remains consistent. Reported-by: Ben Hutchings Closes: https://lore.kernel.org/all/6fe17868327207e8b850cf9f88b7dc58b2021f73.camel@decadent.org.uk/ Fixes: f5bae2642e3d ("hwmon: Driver for MAX16065 System Manager and compatibles") Fixes: b8d5acdcf525 ("hwmon: (max16065) Use local variable to avoid TOCTOU") Cc: stable@vger.kernel.org Signed-off-by: Gui-Dong Han Link: https://lore.kernel.org/r/20260203121443.5482-1-hanguidong02@gmail.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/hwmon/max16065.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/drivers/hwmon/max16065.c b/drivers/hwmon/max16065.c index 4c9e7892a73c1..43fbb9b26b102 100644 --- a/drivers/hwmon/max16065.c +++ b/drivers/hwmon/max16065.c @@ -151,27 +151,27 @@ static struct max16065_data *max16065_update_device(struct device *dev) int i; for (i = 0; i < data->num_adc; i++) - data->adc[i] - = max16065_read_adc(client, MAX16065_ADC(i)); + WRITE_ONCE(data->adc[i], + max16065_read_adc(client, MAX16065_ADC(i))); if (data->have_current) { - data->adc[MAX16065_NUM_ADC] - = max16065_read_adc(client, MAX16065_CSP_ADC); - data->curr_sense - = i2c_smbus_read_byte_data(client, - MAX16065_CURR_SENSE); + WRITE_ONCE(data->adc[MAX16065_NUM_ADC], + max16065_read_adc(client, MAX16065_CSP_ADC)); + WRITE_ONCE(data->curr_sense, + i2c_smbus_read_byte_data(client, MAX16065_CURR_SENSE)); } for (i = 0; i < 2; i++) - data->fault[i] - = i2c_smbus_read_byte_data(client, MAX16065_FAULT(i)); + WRITE_ONCE(data->fault[i], + i2c_smbus_read_byte_data(client, MAX16065_FAULT(i))); /* * MAX16067 and MAX16068 have separate undervoltage and * overvoltage alarm bits. Squash them together. */ if (data->chip == max16067 || data->chip == max16068) - data->fault[0] |= data->fault[1]; + WRITE_ONCE(data->fault[0], + data->fault[0] | data->fault[1]); data->last_updated = jiffies; data->valid = true; @@ -185,7 +185,7 @@ static ssize_t max16065_alarm_show(struct device *dev, { struct sensor_device_attribute_2 *attr2 = to_sensor_dev_attr_2(da); struct max16065_data *data = max16065_update_device(dev); - int val = data->fault[attr2->nr]; + int val = READ_ONCE(data->fault[attr2->nr]); if (val < 0) return val; @@ -203,7 +203,7 @@ static ssize_t max16065_input_show(struct device *dev, { struct sensor_device_attribute *attr = to_sensor_dev_attr(da); struct max16065_data *data = max16065_update_device(dev); - int adc = data->adc[attr->index]; + int adc = READ_ONCE(data->adc[attr->index]); if (unlikely(adc < 0)) return adc; @@ -216,7 +216,7 @@ static ssize_t max16065_current_show(struct device *dev, struct device_attribute *da, char *buf) { struct max16065_data *data = max16065_update_device(dev); - int curr_sense = data->curr_sense; + int curr_sense = READ_ONCE(data->curr_sense); if (unlikely(curr_sense < 0)) return curr_sense; -- 2.51.0