DivestOS/Patches/Linux_CVEs/CVE-2016-10294/ANY/0.patch

From 9e9bc51ffb8a298f0be5befe346762cdb6e1d49c Mon Sep 17 00:00:00 2001
From: ansharma <ansharma@codeaurora.org>
Date: Wed, 18 Jan 2017 16:46:38 +0530
Subject: power: qpnp-fg: Fix possible race condition in FG debugfs

There is a possible race condition when FG debugfs files are concurrently
accessed by multiple threads. Fix this.

CRs-Fixed: 1105481
Change-Id: I154e7f3cdd8d51cf67ef1dfd9d78f423f183cb64
Signed-off-by: ansharma <ansharma@codeaurora.org>
---
 drivers/power/qpnp-fg.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/power/qpnp-fg.c b/drivers/power/qpnp-fg.c
index 182b562..1e2fefc 100644
--- a/drivers/power/qpnp-fg.c
+++ b/drivers/power/qpnp-fg.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2014-2016, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2014-2017, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -669,6 +669,7 @@ struct fg_trans {
 	struct fg_chip *chip;
 	struct fg_log_buffer *log; /* log buffer */
 	u8 *data;	/* fg data that is read */
+	struct mutex memif_dfs_lock; /* Prevent thread concurrency */
 };
 
 struct fg_dbgfs {
@@ -7514,6 +7515,7 @@ static int fg_memif_data_open(struct inode *inode, struct file *file)
 	trans->addr = dbgfs_data.addr;
 	trans->chip = dbgfs_data.chip;
 	trans->offset = trans->addr;
+	mutex_init(&trans->memif_dfs_lock);
 
 	file->private_data = trans;
 	return 0;
@@ -7525,6 +7527,7 @@ static int fg_memif_dfs_close(struct inode *inode, struct file *file)
 
 	if (trans && trans->log && trans->data) {
 		file->private_data = NULL;
+		mutex_destroy(&trans->memif_dfs_lock);
 		kfree(trans->log);
 		kfree(trans->data);
 		kfree(trans);
@@ -7682,10 +7685,13 @@ static ssize_t fg_memif_dfs_reg_read(struct file *file, char __user *buf,
 	size_t ret;
 	size_t len;
 
+	mutex_lock(&trans->memif_dfs_lock);
 	/* Is the the log buffer empty */
 	if (log->rpos >= log->wpos) {
-		if (get_log_data(trans) <= 0)
-			return 0;
+		if (get_log_data(trans) <= 0) {
+			len = 0;
+			goto unlock_mutex;
+		}
 	}
 
 	len = min(count, log->wpos - log->rpos);
@@ -7693,7 +7699,8 @@ static ssize_t fg_memif_dfs_reg_read(struct file *file, char __user *buf,
 	ret = copy_to_user(buf, &log->data[log->rpos], len);
 	if (ret == len) {
 		pr_err("error copy sram register values to user\n");
-		return -EFAULT;
+		len = -EFAULT;
+		goto unlock_mutex;
 	}
 
 	/* 'ret' is the number of bytes not copied */
@@ -7701,6 +7708,9 @@ static ssize_t fg_memif_dfs_reg_read(struct file *file, char __user *buf,
 
 	*ppos += len;
 	log->rpos += len;
+
+unlock_mutex:
+	mutex_unlock(&trans->memif_dfs_lock);
 	return len;
 }
 
@@ -7721,14 +7731,20 @@ static ssize_t fg_memif_dfs_reg_write(struct file *file, const char __user *buf,
 	int cnt = 0;
 	u8  *values;
 	size_t ret = 0;
+	char *kbuf;
+	u32 offset;
 
 	struct fg_trans *trans = file->private_data;
-	u32 offset = trans->offset;
+
+	mutex_lock(&trans->memif_dfs_lock);
+	offset = trans->offset;
 
 	/* Make a copy of the user data */
-	char *kbuf = kmalloc(count + 1, GFP_KERNEL);
-	if (!kbuf)
-		return -ENOMEM;
+	kbuf = kmalloc(count + 1, GFP_KERNEL);
+	if (!kbuf) {
+		ret = -ENOMEM;
+		goto unlock_mutex;
+	}
 
 	ret = copy_from_user(kbuf, buf, count);
 	if (ret == count) {
@@ -7767,6 +7783,8 @@ static ssize_t fg_memif_dfs_reg_write(struct file *file, const char __user *buf,
 
 free_buf:
 	kfree(kbuf);
+unlock_mutex:
+	mutex_unlock(&trans->memif_dfs_lock);
 	return ret;
 }
 
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