Commit a93e7b33 authored by Hamish Martin's avatar Hamish Martin Committed by Greg Kroah-Hartman

uio: Prevent device destruction while fds are open

Prevent destruction of a uio_device while user space apps hold open
file descriptors to that device. Further, access to the 'info' member
of the struct uio_device is protected by spinlock. This is to ensure
stale pointers to data not under control of the UIO subsystem are not
dereferenced.
Signed-off-by: default avatarHamish Martin <hamish.martin@alliedtelesis.co.nz>
Reviewed-by: default avatarChris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 81daa406
......@@ -270,7 +270,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
if (!map_found) {
map_found = 1;
idev->map_dir = kobject_create_and_add("maps",
&idev->dev->kobj);
&idev->dev.kobj);
if (!idev->map_dir) {
ret = -ENOMEM;
goto err_map;
......@@ -299,7 +299,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
if (!portio_found) {
portio_found = 1;
idev->portio_dir = kobject_create_and_add("portio",
&idev->dev->kobj);
&idev->dev.kobj);
if (!idev->portio_dir) {
ret = -ENOMEM;
goto err_portio;
......@@ -342,7 +342,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
kobject_put(&map->kobj);
}
kobject_put(idev->map_dir);
dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
dev_err(&idev->dev, "error creating sysfs files (%d)\n", ret);
return ret;
}
......@@ -379,7 +379,7 @@ static int uio_get_minor(struct uio_device *idev)
idev->minor = retval;
retval = 0;
} else if (retval == -ENOSPC) {
dev_err(idev->dev, "too many uio devices\n");
dev_err(&idev->dev, "too many uio devices\n");
retval = -EINVAL;
}
mutex_unlock(&minor_lock);
......@@ -433,6 +433,7 @@ static int uio_open(struct inode *inode, struct file *filep)
struct uio_device *idev;
struct uio_listener *listener;
int ret = 0;
unsigned long flags;
mutex_lock(&minor_lock);
idev = idr_find(&uio_idr, iminor(inode));
......@@ -442,9 +443,11 @@ static int uio_open(struct inode *inode, struct file *filep)
goto out;
}
get_device(&idev->dev);
if (!try_module_get(idev->owner)) {
ret = -ENODEV;
goto out;
goto err_module_get;
}
listener = kmalloc(sizeof(*listener), GFP_KERNEL);
......@@ -457,11 +460,13 @@ static int uio_open(struct inode *inode, struct file *filep)
listener->event_count = atomic_read(&idev->event);
filep->private_data = listener;
if (idev->info->open) {
spin_lock_irqsave(&idev->info_lock, flags);
if (idev->info && idev->info->open)
ret = idev->info->open(idev->info, inode);
if (ret)
goto err_infoopen;
}
spin_unlock_irqrestore(&idev->info_lock, flags);
if (ret)
goto err_infoopen;
return 0;
err_infoopen:
......@@ -470,6 +475,9 @@ static int uio_open(struct inode *inode, struct file *filep)
err_alloc_listener:
module_put(idev->owner);
err_module_get:
put_device(&idev->dev);
out:
return ret;
}
......@@ -487,12 +495,16 @@ static int uio_release(struct inode *inode, struct file *filep)
int ret = 0;
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
unsigned long flags;
if (idev->info->release)
spin_lock_irqsave(&idev->info_lock, flags);
if (idev->info && idev->info->release)
ret = idev->info->release(idev->info, inode);
spin_unlock_irqrestore(&idev->info_lock, flags);
module_put(idev->owner);
kfree(listener);
put_device(&idev->dev);
return ret;
}
......@@ -500,9 +512,16 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
{
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
__poll_t ret = 0;
unsigned long flags;
if (!idev->info->irq)
return -EIO;
spin_lock_irqsave(&idev->info_lock, flags);
if (!idev->info || !idev->info->irq)
ret = -EIO;
spin_unlock_irqrestore(&idev->info_lock, flags);
if (ret)
return ret;
poll_wait(filep, &idev->wait, wait);
if (listener->event_count != atomic_read(&idev->event))
......@@ -516,11 +535,17 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
DECLARE_WAITQUEUE(wait, current);
ssize_t retval;
ssize_t retval = 0;
s32 event_count;
unsigned long flags;
if (!idev->info->irq)
return -EIO;
spin_lock_irqsave(&idev->info_lock, flags);
if (!idev->info || !idev->info->irq)
retval = -EIO;
spin_unlock_irqrestore(&idev->info_lock, flags);
if (retval)
return retval;
if (count != sizeof(s32))
return -EINVAL;
......@@ -567,8 +592,10 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
struct uio_device *idev = listener->dev;
ssize_t retval;
s32 irq_on;
unsigned long flags;
if (!idev->info->irq) {
spin_lock_irqsave(&idev->info_lock, flags);
if (!idev->info || !idev->info->irq) {
retval = -EIO;
goto out;
}
......@@ -591,6 +618,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
retval = idev->info->irqcontrol(idev->info, irq_on);
out:
spin_unlock_irqrestore(&idev->info_lock, flags);
return retval ? retval : sizeof(s32);
}
......@@ -803,6 +831,13 @@ static void release_uio_class(void)
uio_major_cleanup();
}
static void uio_device_release(struct device *dev)
{
struct uio_device *idev = dev_get_drvdata(dev);
kfree(idev);
}
/**
* uio_register_device - register a new userspace IO device
* @owner: module that creates the new device
......@@ -823,13 +858,14 @@ int __uio_register_device(struct module *owner,
info->uio_dev = NULL;
idev = devm_kzalloc(parent, sizeof(*idev), GFP_KERNEL);
idev = kzalloc(sizeof(*idev), GFP_KERNEL);
if (!idev) {
return -ENOMEM;
}
idev->owner = owner;
idev->info = info;
spin_lock_init(&idev->info_lock);
init_waitqueue_head(&idev->wait);
atomic_set(&idev->event, 0);
......@@ -837,14 +873,19 @@ int __uio_register_device(struct module *owner,
if (ret)
return ret;
idev->dev = device_create(&uio_class, parent,
MKDEV(uio_major, idev->minor), idev,
"uio%d", idev->minor);
if (IS_ERR(idev->dev)) {
printk(KERN_ERR "UIO: device register failed\n");
ret = PTR_ERR(idev->dev);
idev->dev.devt = MKDEV(uio_major, idev->minor);
idev->dev.class = &uio_class;
idev->dev.parent = parent;
idev->dev.release = uio_device_release;
dev_set_drvdata(&idev->dev, idev);
ret = dev_set_name(&idev->dev, "uio%d", idev->minor);
if (ret)
goto err_device_create;
ret = device_register(&idev->dev);
if (ret)
goto err_device_create;
}
ret = uio_dev_add_attributes(idev);
if (ret)
......@@ -872,7 +913,7 @@ int __uio_register_device(struct module *owner,
err_request_irq:
uio_dev_del_attributes(idev);
err_uio_dev_add_attributes:
device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
device_unregister(&idev->dev);
err_device_create:
uio_free_minor(idev);
return ret;
......@@ -887,6 +928,7 @@ EXPORT_SYMBOL_GPL(__uio_register_device);
void uio_unregister_device(struct uio_info *info)
{
struct uio_device *idev;
unsigned long flags;
if (!info || !info->uio_dev)
return;
......@@ -900,7 +942,11 @@ void uio_unregister_device(struct uio_info *info)
if (info->irq && info->irq != UIO_IRQ_CUSTOM)
free_irq(info->irq, idev);
device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
spin_lock_irqsave(&idev->info_lock, flags);
idev->info = NULL;
spin_unlock_irqrestore(&idev->info_lock, flags);
device_unregister(&idev->dev);
return;
}
......
......@@ -14,6 +14,7 @@
#ifndef _UIO_DRIVER_H_
#define _UIO_DRIVER_H_
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
......@@ -68,12 +69,13 @@ struct uio_port {
struct uio_device {
struct module *owner;
struct device *dev;
struct device dev;
int minor;
atomic_t event;
struct fasync_struct *async_queue;
wait_queue_head_t wait;
struct uio_info *info;
spinlock_t info_lock;
struct kobject *map_dir;
struct kobject *portio_dir;
};
......
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