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FAILED: patch "[PATCH] iio:humidity:hts221 Fix alignment and data leak issues" failed to apply to 4.14-stable tree

PATCH [email protected] 1 participant 1 message Jul 17, 2020

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Stable branch IIO HTS221 temperature-humidity IIO driver
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The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5c49056ad9f3c786f7716da2dd47e4488fc6bd25 Mon Sep 17 00:00:00 2001
From: Jonathan Cameron <[email protected]>
Date: Sun, 7 Jun 2020 16:53:53 +0100
Subject: [PATCH] iio:humidity:hts221 Fix alignment and data leak issues

One of a class of bugs pointed out by Lars in a recent review. iio_push_to_buffers_with_timestamp assumes the buffer used is aligned to the size of the timestamp (8 bytes). This is not guaranteed in this driver which uses an array of smaller elements on the stack. As Lars also noted this anti pattern can involve a leak of data to userspace and that indeed can happen here. We close both issues by moving to a suitable structure in the iio_priv() data. This data is allocated with kzalloc so no data can leak apart from previous readings.

Explicit alignment of ts needed to ensure consistent padding on all architectures (particularly x86_32 with it's 4 byte alignment of s64)

Fixes e4a70e3e7d84 ("iio: humidity: add support to hts221 rh/temp combo device")
Reported-by Lars-Peter Clausen <[email protected]>
Acked-by Lorenzo Bianconi <[email protected]>
Signed-off-by Jonathan Cameron <[email protected]>
Cc <[email protected]>
drivers/iio/humidity/hts221.h +5 -2
index 7d6771f7cf47..b2eb5abeaccd 100644
@@ -14,8 +14,6 @@
 
 #include <linux/iio/iio.h>
 
-#define HTS221_DATA_SIZE	2
-
 enum hts221_sensor_type {
 	HTS221_SENSOR_H,
 	HTS221_SENSOR_T,

@@ -39,6 +37,11 @@ struct hts221_hw {
 
 	bool enabled;
 	u8 odr;
+	/* Ensure natural alignment of timestamp */
+	struct {
+		__le16 channels[2];
+		s64 ts __aligned(8);
+	} scan;
 };
 
 extern const struct dev_pm_ops hts221_pm_ops;
drivers/iio/humidity/hts221_buffer.c +5 -4
index 9fb3f33614d4..ba7d413d75ba 100644
@@ -160,7 +160,6 @@ static const struct iio_buffer_setup_ops hts221_buffer_ops = {
 
 static irqreturn_t hts221_buffer_handler_thread(int irq, void *p)
 {
-	u8 buffer[ALIGN(2 * HTS221_DATA_SIZE, sizeof(s64)) + sizeof(s64)];
 	struct iio_poll_func *pf = p;
 	struct iio_dev *iio_dev = pf->indio_dev;
 	struct hts221_hw *hw = iio_priv(iio_dev);

@@ -170,18 +169,20 @@ static irqreturn_t hts221_buffer_handler_thread(int irq, void *p)
 	/* humidity data */
 	ch = &iio_dev->channels[HTS221_SENSOR_H];
 	err = regmap_bulk_read(hw->regmap, ch->address,
-			       buffer, HTS221_DATA_SIZE);
+			       &hw->scan.channels[0],
+			       sizeof(hw->scan.channels[0]));
 	if (err < 0)
 		goto out;
 
 	/* temperature data */
 	ch = &iio_dev->channels[HTS221_SENSOR_T];
 	err = regmap_bulk_read(hw->regmap, ch->address,
-			       buffer + HTS221_DATA_SIZE, HTS221_DATA_SIZE);
+			       &hw->scan.channels[1],
+			       sizeof(hw->scan.channels[1]));
 	if (err < 0)
 		goto out;
 
-	iio_push_to_buffers_with_timestamp(iio_dev, buffer,
+	iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan,
 					   iio_get_time_ns(iio_dev));
 
 out: