DivestOS/Patches/Linux_CVEs/CVE-2016-6745/ANY/3.patch

From 19055017169363f176693c3e41ebdfc3c8e11ef4 Mon Sep 17 00:00:00 2001
From: Andrew Chant <achant@google.com>
Date: Thu, 15 Sep 2016 12:10:56 -0700
Subject: [PATCH] input: touchscreen: synaptics: prevent sysfs races

Concurrent sysfs calls can cause ugly race conditions.
Return EBUSY on concurrent sysfs calls, and prevent sysfs calls
during initial fw load.

Change-Id: I5e295c4cd7c3ba4b998de5b75f9b631679e7c39f
Signed-off-by: Andrew Chant <achant@google.com>
Bug: 31252388
---
 .../synaptics_dsx25/synaptics_dsx_fw_update.c      | 138 +++++++++++++++------
 1 file changed, 99 insertions(+), 39 deletions(-)

diff --git a/drivers/input/touchscreen/synaptics_dsx25/synaptics_dsx_fw_update.c b/drivers/input/touchscreen/synaptics_dsx25/synaptics_dsx_fw_update.c
index 3edeaa22aa336..908693bd26a43 100755
--- a/drivers/input/touchscreen/synaptics_dsx25/synaptics_dsx_fw_update.c
+++ b/drivers/input/touchscreen/synaptics_dsx25/synaptics_dsx_fw_update.c
@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
+#include <linux/mutex.h>
 #include <linux/delay.h>
 #include <linux/input.h>
 #include <linux/firmware.h>
@@ -654,6 +655,7 @@ static struct device_attribute attrs[] = {
 static struct synaptics_rmi4_fwu_handle *fwu;
 
 DECLARE_COMPLETION(dsx_fwu_remove_complete);
+DEFINE_MUTEX(fwu_sysfs_mutex);
 
 static bool tp_2k_panel = false;
 /**
@@ -3719,14 +3721,18 @@ static ssize_t fwu_sysfs_show_image(struct file *data_file,
 		struct kobject *kobj, struct bin_attribute *attributes,
 		char *buf, loff_t pos, size_t count)
 {
-	int retval;
+	ssize_t retval;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	if (count < fwu->config_size) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Not enough space (%zu bytes) in buffer\n",
 				__func__, count);
-		return -EINVAL;
+		retval = -EINVAL;
+		goto show_image_exit;
 	}
 
 	retval = secure_memcpy(buf, count, fwu->read_config_buf,
@@ -3735,43 +3741,56 @@ static ssize_t fwu_sysfs_show_image(struct file *data_file,
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to copy config data\n",
 				__func__);
-		return retval;
+		goto show_image_exit;
 	}
 
-	return fwu->config_size;
+	retval = fwu->config_size;
+
+show_image_exit:
+	mutex_unlock(&fwu_sysfs_mutex);
+	return retval;
 }
 
 static ssize_t fwu_sysfs_store_image(struct file *data_file,
 		struct kobject *kobj, struct bin_attribute *attributes,
 		char *buf, loff_t pos, size_t count)
 {
-	int retval;
+	ssize_t retval;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	retval = secure_memcpy(&fwu->ext_data_source[fwu->data_pos],
 			fwu->image_size - fwu->data_pos, buf, count, count);
 	if (retval < 0) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to copy image data\n",
 				__func__);
-		return retval;
+		goto store_image_exit;
 	}
 
 	fwu->data_pos += count;
+	retval = count;
 
+store_image_exit:
+	mutex_unlock(&fwu_sysfs_mutex);
 	return count;
 }
 
 static ssize_t fwu_sysfs_do_recovery_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
-	int retval;
+	ssize_t retval;
 	unsigned int input;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	if (sscanf(buf, "%u", &input) != 1) {
 		retval = -EINVAL;
-		goto exit;
+		goto recovery_store_exit;
 	}
 
 	if (!fwu->in_ub_mode) {
@@ -3779,28 +3798,32 @@ static ssize_t fwu_sysfs_do_recovery_store(struct device *dev,
 				"%s: Not in microbootloader mode\n",
 				__func__);
 		retval = -EINVAL;
-		goto exit;
+		goto recovery_store_exit;
 	}
 
-	if (!fwu->ext_data_source)
-		return -EINVAL;
-	else
+	if (!fwu->ext_data_source) {
+		retval = -EINVAL;
+		goto recovery_store_exit;
+	} else {
 		fwu->image = fwu->ext_data_source;
+	}
 
 	retval = fwu_start_recovery();
 	if (retval < 0) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to do recovery\n",
 				__func__);
-		goto exit;
+		goto recovery_store_free_exit;
 	}
 
 	retval = count;
 
-exit:
+recovery_store_free_exit:
 	kfree(fwu->ext_data_source);
 	fwu->ext_data_source = NULL;
 	fwu->image = NULL;
+recovery_store_exit:
+	mutex_unlock(&fwu_sysfs_mutex);
 	return retval;
 }
 
@@ -3811,15 +3834,20 @@ static ssize_t fwu_sysfs_do_reflash_store(struct device *dev,
 	unsigned int input;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	if (sscanf(buf, "%u", &input) != 1) {
 		retval = -EINVAL;
-		goto exit;
+		goto reflash_store_exit;
 	}
 
-	if (!fwu->ext_data_source)
-		return -EINVAL;
-	else
+	if (!fwu->ext_data_source) {
+		retval = -EINVAL;
+		goto reflash_store_exit;
+	} else {
 		fwu->image = fwu->ext_data_source;
+	}
 
 	if (input & LOCKDOWN) {
 		fwu->do_lockdown = true;
@@ -3828,7 +3856,7 @@ static ssize_t fwu_sysfs_do_reflash_store(struct device *dev,
 
 	if ((input != NORMAL) && (input != FORCE)) {
 		retval = -EINVAL;
-		goto exit;
+		goto reflash_store_exit;
 	}
 
 	if (input == FORCE)
@@ -3839,17 +3867,19 @@ static ssize_t fwu_sysfs_do_reflash_store(struct device *dev,
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to do reflash\n",
 				__func__);
-		goto exit;
+		goto reflash_store_free_exit;
 	}
 
 	retval = count;
 
-exit:
+reflash_store_free_exit:
 	kfree(fwu->ext_data_source);
 	fwu->ext_data_source = NULL;
 	fwu->image = NULL;
 	fwu->force_update = FORCE_UPDATE;
 	fwu->do_lockdown = DO_LOCKDOWN;
+reflash_store_exit:
+	mutex_unlock(&fwu_sysfs_mutex);
 	return retval;
 }
 
@@ -3860,35 +3890,42 @@ static ssize_t fwu_sysfs_write_config_store(struct device *dev,
 	unsigned int input;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	if (sscanf(buf, "%u", &input) != 1) {
 		retval = -EINVAL;
-		goto exit;
+		goto write_config_store_exit;
 	}
 
 	if (input != 1) {
 		retval = -EINVAL;
-		goto exit;
+		goto write_config_store_exit;
 	}
 
-	if (!fwu->ext_data_source)
-		return -EINVAL;
-	else
+	if (!fwu->ext_data_source) {
+		retval = -EINVAL;
+		goto write_config_store_exit;
+	} else {
 		fwu->image = fwu->ext_data_source;
+	}
 
 	retval = fwu_start_write_config();
 	if (retval < 0) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to write config\n",
 				__func__);
-		goto exit;
+		goto write_config_store_free_exit;
 	}
 
 	retval = count;
 
-exit:
+write_config_store_free_exit:
 	kfree(fwu->ext_data_source);
 	fwu->ext_data_source = NULL;
 	fwu->image = NULL;
+write_config_store_exit:
+	mutex_unlock(&fwu_sysfs_mutex);
 	return retval;
 }
 
@@ -3905,7 +3942,11 @@ static ssize_t fwu_sysfs_read_config_store(struct device *dev,
 	if (input != 1)
 		return -EINVAL;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
 	retval = fwu_do_read_config();
+	mutex_unlock(&fwu_sysfs_mutex);
+
 	if (retval < 0) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to read config\n",
@@ -3926,7 +3967,10 @@ static ssize_t fwu_sysfs_config_area_store(struct device *dev,
 	if (retval)
 		return retval;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
 	fwu->config_area = config_area;
+	mutex_unlock(&fwu_sysfs_mutex);
 
 	return count;
 }
@@ -3937,8 +3981,12 @@ static ssize_t fwu_sysfs_image_name_store(struct device *dev,
 	int retval;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
 	retval = secure_memcpy(fwu->image_name, MAX_IMAGE_NAME_LEN,
 			buf, count, count);
+	mutex_unlock(&fwu_sysfs_mutex);
+
 	if (retval < 0) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to copy image file name\n",
@@ -3952,7 +4000,7 @@ static ssize_t fwu_sysfs_image_name_store(struct device *dev,
 static ssize_t fwu_sysfs_image_size_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
-	int retval;
+	ssize_t retval;
 	unsigned long size;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
@@ -3960,6 +4008,9 @@ static ssize_t fwu_sysfs_image_size_store(struct device *dev,
 	if (retval)
 		return retval;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	fwu->image_size = size;
 	fwu->data_pos = 0;
 
@@ -3969,10 +4020,12 @@ static ssize_t fwu_sysfs_image_size_store(struct device *dev,
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to alloc mem for image data\n",
 				__func__);
-		return -ENOMEM;
+		retval = -ENOMEM;
+	} else {
+		retval = count;
 	}
-
-	return count;
+	mutex_unlock(&fwu_sysfs_mutex);
+	return retval;
 }
 
 static ssize_t fwu_sysfs_block_size_show(struct device *dev,
@@ -4024,35 +4077,42 @@ static ssize_t fwu_sysfs_write_guest_code_store(struct device *dev,
 	unsigned int input;
 	struct synaptics_rmi4_data *rmi4_data = fwu->rmi4_data;
 
+	if (!mutex_trylock(&fwu_sysfs_mutex))
+		return -EBUSY;
+
 	if (sscanf(buf, "%u", &input) != 1) {
 		retval = -EINVAL;
-		goto exit;
+		goto guest_code_store_exit;
 	}
 
 	if (input != 1) {
 		retval = -EINVAL;
-		goto exit;
+		goto guest_code_store_exit;
 	}
 
-	if (!fwu->ext_data_source)
-		return -EINVAL;
-	else
+	if (!fwu->ext_data_source) {
+		retval = -EINVAL;
+		goto guest_code_store_exit;
+	} else {
 		fwu->image = fwu->ext_data_source;
+	}
 
 	retval = fwu_start_write_guest_code();
 	if (retval < 0) {
 		dev_err(rmi4_data->pdev->dev.parent,
 				"%s: Failed to write guest code\n",
 				__func__);
-		goto exit;
+		goto guest_code_store_free_exit;
 	}
 
 	retval = count;
 
-exit:
+guest_code_store_free_exit:
 	kfree(fwu->ext_data_source);
 	fwu->ext_data_source = NULL;
 	fwu->image = NULL;
+guest_code_store_exit:
+	mutex_unlock(&fwu_sysfs_mutex);
 	return retval;
 }