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authorHamish Martin <hamish.martin@alliedtelesis.co.nz>2019-02-13 16:29:29 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-15 08:09:14 +0100
commit085d735c858934e5d5bfaedb1fc98bd9135e6ff1 (patch)
tree435a1d4dd78eaf453c33c7af23e95289c32a420c
parentcd4fe6339ccd9638da1304160abe60b84115dee5 (diff)
uio: Prevent device destruction while fds are open
commit a93e7b331568227500186a465fee3c2cb5dffd1f upstream. 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> [4.14 change __poll_t to unsigned int] Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/uio/uio.c98
-rw-r--r--include/linux/uio_driver.h4
2 files changed, 75 insertions, 27 deletions
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 10f249628e79..288c4b977184 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -272,7 +272,7 @@ 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;
@@ -301,7 +301,7 @@ 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;
@@ -344,7 +344,7 @@ err_map_kobj:
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;
}
@@ -381,7 +381,7 @@ 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);
@@ -435,6 +435,7 @@ 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));
@@ -444,9 +445,11 @@ 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);
@@ -459,11 +462,13 @@ 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:
@@ -472,6 +477,9 @@ err_infoopen:
err_alloc_listener:
module_put(idev->owner);
+err_module_get:
+ put_device(&idev->dev);
+
out:
return ret;
}
@@ -489,12 +497,16 @@ 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;
}
@@ -502,9 +514,16 @@ static unsigned int uio_poll(struct file *filep, poll_table *wait)
{
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
+ unsigned int 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))
@@ -518,11 +537,17 @@ 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;
@@ -569,8 +594,10 @@ 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;
}
@@ -593,6 +620,7 @@ 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);
}
@@ -809,6 +837,13 @@ 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
@@ -832,13 +867,14 @@ 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);
@@ -846,14 +882,19 @@ 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)
@@ -883,7 +924,7 @@ 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;
@@ -898,6 +939,7 @@ 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;
@@ -911,7 +953,11 @@ 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;
}
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 3c85c81b0027..6c5f2074e14f 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -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;
};