DivestOS/Patches/Linux_CVEs/CVE-2017-0536/ANY/0001.patch

From e6430a4da1fb0212a546379eadbe986f629c3ae9 Mon Sep 17 00:00:00 2001
From: Andrew Chant <achant@google.com>
Date: Fri, 13 Jan 2017 11:41:03 -0800
Subject: [PATCH] input: synaptics_dsx: protect tmpbuf allocation.

Protect tmpbuf from concurrent access by mutex.

BUG: 33555878
BUG: 33002026
Change-Id: Ia7eeb59ca7b626f416e2298b4b9ffd960fe909e4
Signed-off-by: Andrew Chant <achant@google.com>
---
 .../synaptics_dsx_htc_2.6/synaptics_dsx_rmi_dev.c  | 36 ++++++++++++++--------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/input/touchscreen/synaptics_dsx_htc_2.6/synaptics_dsx_rmi_dev.c b/drivers/input/touchscreen/synaptics_dsx_htc_2.6/synaptics_dsx_rmi_dev.c
index e699dfea50c81..6878b71da9be0 100644
--- a/drivers/input/touchscreen/synaptics_dsx_htc_2.6/synaptics_dsx_rmi_dev.c
+++ b/drivers/input/touchscreen/synaptics_dsx_htc_2.6/synaptics_dsx_rmi_dev.c
@@ -565,18 +565,24 @@ static ssize_t rmidev_read(struct file *filp, char __user *buf,
 		return -EBADF;
 	}
 
-	if (count == 0)
-		return 0;
+	mutex_lock(&(dev_data->file_mutex));
+
+	if (*f_pos > REG_ADDR_LIMIT) {
+		retval = -EFAULT;
+		goto clean_up;
+	}
 
 	if (count > (REG_ADDR_LIMIT - *f_pos))
 		count = REG_ADDR_LIMIT - *f_pos;
 
+	if (count == 0) {
+		retval = 0;
+		goto clean_up;
+	}
 	address = (unsigned short)(*f_pos);
 
 	rmidev_allocate_buffer(count);
 
-	mutex_lock(&(dev_data->file_mutex));
-
 	retval = synaptics_rmi4_reg_read(rmidev->rmi4_data,
 			*f_pos,
 			rmidev->tmpbuf,
@@ -636,19 +642,25 @@ static ssize_t rmidev_write(struct file *filp, const char __user *buf,
 		return -EBADF;
 	}
 
-	if (count == 0)
-		return 0;
+	mutex_lock(&(dev_data->file_mutex));
 
+	if (*f_pos > REG_ADDR_LIMIT) {
+		retval = -EFAULT;
+		goto unlock;
+	}
 	if (count > (REG_ADDR_LIMIT - *f_pos))
 		count = REG_ADDR_LIMIT - *f_pos;
+	if (count == 0) {
+		retval = 0;
+		goto unlock;
+	}
 
 	rmidev_allocate_buffer(count);
 
-	if (copy_from_user(rmidev->tmpbuf, buf, count))
-		return -EFAULT;
-
-	mutex_lock(&(dev_data->file_mutex));
-
+	if (copy_from_user(rmidev->tmpbuf, buf, count)) {
+		retval = -EFAULT;
+		goto unlock;
+	}
 	retval = synaptics_rmi4_reg_write(rmidev->rmi4_data,
 			*f_pos,
 			rmidev->tmpbuf,
@@ -656,8 +668,8 @@ static ssize_t rmidev_write(struct file *filp, const char __user *buf,
 	if (retval >= 0)
 		*f_pos += retval;
 
+unlock:
 	mutex_unlock(&(dev_data->file_mutex));
-
 	return retval;
 }