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uio: Prevent device destruction while fds are open

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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: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hamish Martin 2018-05-14 13:32:23 +12:00 committed by Greg Kroah-Hartman
parent 81daa406c2
commit a93e7b3315
2 changed files with 75 additions and 27 deletions
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98
drivers/uio/uio.c
View File

@ -270,7 +270,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
if (!map_found) { if (!map_found) {
map_found = 1; map_found = 1;
idev->map_dir = kobject_create_and_add("maps", idev->map_dir = kobject_create_and_add("maps",
&idev->dev->kobj); &idev->dev.kobj);
if (!idev->map_dir) { if (!idev->map_dir) {
ret = -ENOMEM; ret = -ENOMEM;
goto err_map; goto err_map;
@ -299,7 +299,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
if (!portio_found) { if (!portio_found) {
portio_found = 1; portio_found = 1;
idev->portio_dir = kobject_create_and_add("portio", idev->portio_dir = kobject_create_and_add("portio",
&idev->dev->kobj); &idev->dev.kobj);
if (!idev->portio_dir) { if (!idev->portio_dir) {
ret = -ENOMEM; ret = -ENOMEM;
goto err_portio; goto err_portio;
@ -342,7 +342,7 @@ err_map_kobj:
kobject_put(&map->kobj); kobject_put(&map->kobj);
} }
kobject_put(idev->map_dir); 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; return ret;
} }
@ -379,7 +379,7 @@ static int uio_get_minor(struct uio_device *idev)
idev->minor = retval; idev->minor = retval;
retval = 0; retval = 0;
} else if (retval == -ENOSPC) { } else if (retval == -ENOSPC) {
dev_err(idev->dev, "too many uio devices\n"); dev_err(&idev->dev, "too many uio devices\n");
retval = -EINVAL; retval = -EINVAL;
} }
mutex_unlock(&minor_lock); mutex_unlock(&minor_lock);
@ -433,6 +433,7 @@ static int uio_open(struct inode *inode, struct file *filep)
struct uio_device *idev; struct uio_device *idev;
struct uio_listener *listener; struct uio_listener *listener;
int ret = 0; int ret = 0;
unsigned long flags;
mutex_lock(&minor_lock); mutex_lock(&minor_lock);
idev = idr_find(&uio_idr, iminor(inode)); idev = idr_find(&uio_idr, iminor(inode));
@ -442,9 +443,11 @@ static int uio_open(struct inode *inode, struct file *filep)
goto out; goto out;
} }
get_device(&idev->dev);
if (!try_module_get(idev->owner)) { if (!try_module_get(idev->owner)) {
ret = -ENODEV; ret = -ENODEV;
goto out; goto err_module_get;
} }
listener = kmalloc(sizeof(*listener), GFP_KERNEL); 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); listener->event_count = atomic_read(&idev->event);
filep->private_data = listener; 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); ret = idev->info->open(idev->info, inode);
if (ret) spin_unlock_irqrestore(&idev->info_lock, flags);
goto err_infoopen; if (ret)
} goto err_infoopen;
return 0; return 0;
err_infoopen: err_infoopen:
@ -470,6 +475,9 @@ err_infoopen:
err_alloc_listener: err_alloc_listener:
module_put(idev->owner); module_put(idev->owner);
err_module_get:
put_device(&idev->dev);
out: out:
return ret; return ret;
} }
@ -487,12 +495,16 @@ static int uio_release(struct inode *inode, struct file *filep)
int ret = 0; int ret = 0;
struct uio_listener *listener = filep->private_data; struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev; 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); ret = idev->info->release(idev->info, inode);
spin_unlock_irqrestore(&idev->info_lock, flags);
module_put(idev->owner); module_put(idev->owner);
kfree(listener); kfree(listener);
put_device(&idev->dev);
return ret; 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_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev; struct uio_device *idev = listener->dev;
__poll_t ret = 0;
unsigned long flags;
if (!idev->info->irq) spin_lock_irqsave(&idev->info_lock, flags);
return -EIO; 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); poll_wait(filep, &idev->wait, wait);
if (listener->event_count != atomic_read(&idev->event)) 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_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev; struct uio_device *idev = listener->dev;
DECLARE_WAITQUEUE(wait, current); DECLARE_WAITQUEUE(wait, current);
ssize_t retval; ssize_t retval = 0;
s32 event_count; s32 event_count;
unsigned long flags;
if (!idev->info->irq) spin_lock_irqsave(&idev->info_lock, flags);
return -EIO; if (!idev->info || !idev->info->irq)
retval = -EIO;
spin_unlock_irqrestore(&idev->info_lock, flags);
if (retval)
return retval;
if (count != sizeof(s32)) if (count != sizeof(s32))
return -EINVAL; return -EINVAL;
@ -567,8 +592,10 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
struct uio_device *idev = listener->dev; struct uio_device *idev = listener->dev;
ssize_t retval; ssize_t retval;
s32 irq_on; 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; retval = -EIO;
goto out; 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); retval = idev->info->irqcontrol(idev->info, irq_on);
out: out:
spin_unlock_irqrestore(&idev->info_lock, flags);
return retval ? retval : sizeof(s32); return retval ? retval : sizeof(s32);
} }
@ -803,6 +831,13 @@ static void release_uio_class(void)
uio_major_cleanup(); 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 * uio_register_device - register a new userspace IO device
* @owner: module that creates the new device * @owner: module that creates the new device
@ -823,13 +858,14 @@ int __uio_register_device(struct module *owner,
info->uio_dev = NULL; info->uio_dev = NULL;
idev = devm_kzalloc(parent, sizeof(*idev), GFP_KERNEL); idev = kzalloc(sizeof(*idev), GFP_KERNEL);
if (!idev) { if (!idev) {
return -ENOMEM; return -ENOMEM;
} }
idev->owner = owner; idev->owner = owner;
idev->info = info; idev->info = info;
spin_lock_init(&idev->info_lock);
init_waitqueue_head(&idev->wait); init_waitqueue_head(&idev->wait);
atomic_set(&idev->event, 0); atomic_set(&idev->event, 0);
@ -837,14 +873,19 @@ int __uio_register_device(struct module *owner,
if (ret) if (ret)
return ret; return ret;
idev->dev = device_create(&uio_class, parent, idev->dev.devt = MKDEV(uio_major, idev->minor);
MKDEV(uio_major, idev->minor), idev, idev->dev.class = &uio_class;
"uio%d", idev->minor); idev->dev.parent = parent;
if (IS_ERR(idev->dev)) { idev->dev.release = uio_device_release;
printk(KERN_ERR "UIO: device register failed\n"); dev_set_drvdata(&idev->dev, idev);
ret = PTR_ERR(idev->dev);
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; goto err_device_create;
}
ret = uio_dev_add_attributes(idev); ret = uio_dev_add_attributes(idev);
if (ret) if (ret)
@ -872,7 +913,7 @@ int __uio_register_device(struct module *owner,
err_request_irq: err_request_irq:
uio_dev_del_attributes(idev); uio_dev_del_attributes(idev);
err_uio_dev_add_attributes: err_uio_dev_add_attributes:
device_destroy(&uio_class, MKDEV(uio_major, idev->minor)); device_unregister(&idev->dev);
err_device_create: err_device_create:
uio_free_minor(idev); uio_free_minor(idev);
return ret; return ret;
@ -887,6 +928,7 @@ EXPORT_SYMBOL_GPL(__uio_register_device);
void uio_unregister_device(struct uio_info *info) void uio_unregister_device(struct uio_info *info)
{ {
struct uio_device *idev; struct uio_device *idev;
unsigned long flags;
if (!info || !info->uio_dev) if (!info || !info->uio_dev)
return; return;
@ -900,7 +942,11 @@ void uio_unregister_device(struct uio_info *info)
if (info->irq && info->irq != UIO_IRQ_CUSTOM) if (info->irq && info->irq != UIO_IRQ_CUSTOM)
free_irq(info->irq, idev); 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; return;
} }

4
include/linux/uio_driver.h
View File

@ -14,6 +14,7 @@
#ifndef _UIO_DRIVER_H_ #ifndef _UIO_DRIVER_H_
#define _UIO_DRIVER_H_ #define _UIO_DRIVER_H_
#include <linux/device.h>
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/interrupt.h> #include <linux/interrupt.h>
@ -68,12 +69,13 @@ struct uio_port {
struct uio_device { struct uio_device {
struct module *owner; struct module *owner;
struct device *dev; struct device dev;
int minor; int minor;
atomic_t event; atomic_t event;
struct fasync_struct *async_queue; struct fasync_struct *async_queue;
wait_queue_head_t wait; wait_queue_head_t wait;
struct uio_info *info; struct uio_info *info;
spinlock_t info_lock;
struct kobject *map_dir; struct kobject *map_dir;
struct kobject *portio_dir; struct kobject *portio_dir;
}; };