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coresight: tmc: Fix use after free issue with tmc read 

Fix race condition seen between reading tmc buffer and enabling
the device. The race condition can result in a use after free
issue if the buffer is released while a read is in progress.

Signed-off-by: Saranya Chidura <schidura@codeaurora.org>
Change-Id: I9908fa78acbf3152ee791c63fef525f09a9a23d5
This commit is contained in:
Saranya Chidura 2017-07-10 11:52:36 +05:30 committed by Gerrit - the friendly Code Review server
parent 0ee94ed17b
commit f32fe96ca8
1 changed files with 21 additions and 12 deletions
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33
drivers/coresight/coresight-tmc.c
View File

@ -1,4 +1,4 @@
/* Copyright (c) 2012-2015, The Linux Foundation. All rights reserved.
/* Copyright (c) 2012-2017, 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
@ -850,6 +850,14 @@ static int tmc_enable(struct tmc_drvdata *drvdata, enum tmc_mode mode)
return ret;
mutex_lock(&drvdata->usb_lock);
spin_lock_irqsave(&drvdata->spinlock, flags);
if (drvdata->reading) {
ret = -EBUSY;
spin_unlock_irqrestore(&drvdata->spinlock, flags);
goto err0;
}
spin_unlock_irqrestore(&drvdata->spinlock, flags);
if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
coresight_cti_map_trigout(drvdata->cti_flush, 1, 0);
coresight_cti_map_trigin(drvdata->cti_reset, 2, 0);
@ -896,10 +904,6 @@ static int tmc_enable(struct tmc_drvdata *drvdata, enum tmc_mode mode)
}
spin_lock_irqsave(&drvdata->spinlock, flags);
if (drvdata->reading) {
ret = -EBUSY;
goto err1;
}
if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
__tmc_etb_enable(drvdata);
@ -929,11 +933,6 @@ static int tmc_enable(struct tmc_drvdata *drvdata, enum tmc_mode mode)
dev_info(drvdata->dev, "TMC enabled\n");
return 0;
err1:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
if (drvdata->config_type == TMC_CONFIG_TYPE_ETR)
if (drvdata->out_mode == TMC_ETR_OUT_MODE_USB)
usb_qdss_close(drvdata->usbch);
err0:
mutex_unlock(&drvdata->usb_lock);
clk_disable_unprepare(drvdata->clk);
@ -1328,6 +1327,7 @@ static int tmc_read_prepare(struct tmc_drvdata *drvdata)
unsigned long flags;
enum tmc_mode mode;
mutex_lock(&drvdata->usb_lock);
spin_lock_irqsave(&drvdata->spinlock, flags);
if (!drvdata->sticky_enable) {
dev_err(drvdata->dev, "enable tmc once before reading\n");
@ -1358,11 +1358,13 @@ static int tmc_read_prepare(struct tmc_drvdata *drvdata)
out:
drvdata->reading = true;
spin_unlock_irqrestore(&drvdata->spinlock, flags);
mutex_unlock(&drvdata->usb_lock);
dev_info(drvdata->dev, "TMC read start\n");
return 0;
err:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
mutex_unlock(&drvdata->usb_lock);
return ret;
}
@ -1544,8 +1546,12 @@ static ssize_t tmc_read(struct file *file, char __user *data, size_t len,
{
struct tmc_drvdata *drvdata = container_of(file->private_data,
struct tmc_drvdata, miscdev);
char *bufp = drvdata->buf + *ppos;
char *end = (char *)(drvdata->vaddr + drvdata->size);
char *bufp, *end;
mutex_lock(&drvdata->usb_lock);
bufp = drvdata->buf + *ppos;
end = (char *)(drvdata->vaddr + drvdata->size);
if (*ppos + len > drvdata->size)
len = drvdata->size - *ppos;
@ -1572,6 +1578,7 @@ static ssize_t tmc_read(struct file *file, char __user *data, size_t len,
if (copy_to_user(data, bufp, len)) {
dev_dbg(drvdata->dev, "%s: copy_to_user failed\n", __func__);
mutex_unlock(&drvdata->usb_lock);
return -EFAULT;
}
@ -1579,6 +1586,8 @@ static ssize_t tmc_read(struct file *file, char __user *data, size_t len,
out:
dev_dbg(drvdata->dev, "%s: %zu bytes copied, %d bytes left\n",
__func__, len, (int) (drvdata->size - *ppos));
mutex_unlock(&drvdata->usb_lock);
return len;
}