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FAILED: patch "[PATCH] hwmon: (w83793) Fix NULL pointer dereference by removing" failed to apply to 4.19-stable tree

PATCH [email protected] 1 participant 1 message Oct 3, 2021

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Stable branch Hardware monitoring W83793 hardware monitoring driver
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The patch below does not apply to the 4.19-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 dd4d747ef05addab887dc8ff0d6ab9860bbcd783 Mon Sep 17 00:00:00 2001
From: Nadezda Lutovinova <[email protected]>
Date: Tue, 21 Sep 2021 18:51:53 +0300
Subject: [PATCH] hwmon: (w83793) Fix NULL pointer dereference by removing
unnecessary structure field

If driver read tmp value sufficient for
(tmp & 0x08) && (!(tmp & 0x80)) && ((tmp & 0x7) == ((tmp >> 4) & 0x7)) from device then Null pointer dereference occurs.
(It is possible if tmp = 0b0xyz1xyz, where same literals mean same numbers) Also lm75[] does not serve a purpose anymore after switching to devm_i2c_new_dummy_device() in w83791d_detect_subclients().

The patch fixes possible NULL pointer dereference by removing lm75[].

Found by Linux Driver Verification project (linuxtesting.org).

Cc [email protected]
Signed-off-by Nadezda Lutovinova <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
[groeck: Dropped unnecessary continuation lines, fixed multi-line alignments]
Signed-off-by Guenter Roeck <[email protected]>
drivers/hwmon/w83793.c +11 -15
index e7d0484eabe4..1d2854de1cfc 100644
@@ -202,7 +202,6 @@ static inline s8 TEMP_TO_REG(long val, s8 min, s8 max)
 }
 
 struct w83793_data {
-	struct i2c_client *lm75[2];
 	struct device *hwmon_dev;
 	struct mutex update_lock;
 	char valid;			/* !=0 if following fields are valid */

@@ -1566,7 +1565,6 @@ w83793_detect_subclients(struct i2c_client *client)
 	int address = client->addr;
 	u8 tmp;
 	struct i2c_adapter *adapter = client->adapter;
-	struct w83793_data *data = i2c_get_clientdata(client);
 
 	id = i2c_adapter_id(adapter);
 	if (force_subclients[0] == id && force_subclients[1] == address) {

@@ -1586,21 +1584,19 @@ w83793_detect_subclients(struct i2c_client *client)
 	}
 
 	tmp = w83793_read_value(client, W83793_REG_I2C_SUBADDR);
-	if (!(tmp & 0x08))
-		data->lm75[0] = devm_i2c_new_dummy_device(&client->dev, adapter,
-							  0x48 + (tmp & 0x7));
-	if (!(tmp & 0x80)) {
-		if (!IS_ERR(data->lm75[0])
-		    && ((tmp & 0x7) == ((tmp >> 4) & 0x7))) {
-			dev_err(&client->dev,
-				"duplicate addresses 0x%x, "
-				"use force_subclients\n", data->lm75[0]->addr);
-			return -ENODEV;
-		}
-		data->lm75[1] = devm_i2c_new_dummy_device(&client->dev, adapter,
-							  0x48 + ((tmp >> 4) & 0x7));
+
+	if (!(tmp & 0x88) && (tmp & 0x7) == ((tmp >> 4) & 0x7)) {
+		dev_err(&client->dev,
+			"duplicate addresses 0x%x, use force_subclient\n", 0x48 + (tmp & 0x7));
+		return -ENODEV;
 	}
 
+	if (!(tmp & 0x08))
+		devm_i2c_new_dummy_device(&client->dev, adapter, 0x48 + (tmp & 0x7));
+
+	if (!(tmp & 0x80))
+		devm_i2c_new_dummy_device(&client->dev, adapter, 0x48 + ((tmp >> 4) & 0x7));
+
 	return 0;
 }