From 80decd6365deec08c35ecb902a58f9210599b39a Mon Sep 17 00:00:00 2001
From: ansharma <ansharma@codeaurora.org>
Date: Fri, 20 Jan 2017 14:43:57 +0530
Subject: platform: msm: spmi: Fix possible race condition in debugfs
There is a possible race condition when debugfs files are concurrently
accessed by multiple threads. Fix this.
CRs-Fixed: 1106842
Change-Id: Ifd092143f428db3cf73c45ec4f0aaa96318ae165
Signed-off-by: ansharma <ansharma@codeaurora.org>
---
drivers/platform/msm/spmi/spmi-dbgfs.c | 37 +++++++++++++++++++++++++---------
1 file changed, 28 insertions(+), 9 deletions(-)
diff --git a/drivers/platform/msm/spmi/spmi-dbgfs.c b/drivers/platform/msm/spmi/spmi-dbgfs.c
index b0a354b..86f1b0d 100644
--- a/drivers/platform/msm/spmi/spmi-dbgfs.c
+++ b/drivers/platform/msm/spmi/spmi-dbgfs.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2012-2014, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2012-2014, 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
@@ -69,6 +69,7 @@ struct spmi_trans {
u32 addr; /* 20-bit address: SID + PID + Register offset */
u32 offset; /* Offset of last read data */
bool raw_data; /* Set to true for raw data dump */
+ struct mutex spmi_dfs_lock; /* Prevent thread concurrency */
struct spmi_controller *ctrl;
struct spmi_log_buffer *log; /* log buffer */
};
@@ -168,6 +169,7 @@ static int spmi_dfs_open(struct spmi_ctrl_data *ctrl_data, struct file *file)
trans->addr = ctrl_data->addr;
trans->ctrl = ctrl_data->ctrl;
trans->offset = trans->addr;
+ mutex_init(&trans->spmi_dfs_lock);
file->private_data = trans;
return 0;
@@ -197,6 +199,7 @@ static int spmi_dfs_close(struct inode *inode, struct file *file)
if (trans && trans->log) {
file->private_data = NULL;
+ mutex_destroy(&trans->spmi_dfs_lock);
kfree(trans->log);
kfree(trans);
}
@@ -473,14 +476,21 @@ static ssize_t spmi_dfs_reg_write(struct file *file, const char __user *buf,
int cnt = 0;
u8 *values;
size_t ret = 0;
-
+ u32 offset;
+ char *kbuf;
struct spmi_trans *trans = file->private_data;
- u32 offset = trans->offset;
+
+ mutex_lock(&trans->spmi_dfs_lock);
+
+ trans = file->private_data;
+ 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) {
@@ -517,6 +527,8 @@ static ssize_t spmi_dfs_reg_write(struct file *file, const char __user *buf,
free_buf:
kfree(kbuf);
+unlock_mutex:
+ mutex_unlock(&trans->spmi_dfs_lock);
return ret;
}
@@ -537,10 +549,13 @@ static ssize_t spmi_dfs_reg_read(struct file *file, char __user *buf,
size_t ret;
size_t len;
+ mutex_lock(&trans->spmi_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);
@@ -548,7 +563,8 @@ static ssize_t spmi_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 SPMI register values to user\n");
- return -EFAULT;
+ len = -EFAULT;
+ goto unlock_mutex;
}
/* 'ret' is the number of bytes not copied */
@@ -556,6 +572,9 @@ static ssize_t spmi_dfs_reg_read(struct file *file, char __user *buf,
*ppos += len;
log->rpos += len;
+
+unlock_mutex:
+ mutex_unlock(&trans->spmi_dfs_lock);
return len;
}
--
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