UIO: hold a reference to the device's owner while the device is open

Otherwise the device might just disappear while /dev/uioX is being used
which results in an Oops.

Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Signed-off-by: Hans J Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 21 insertions, 15 deletions

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 11759080ca54..55cc7b80422a 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -301,23 +301,33 @@ static int uio_open(struct inode *inode, struct file *filep)
         if (!idev)
                 return -ENODEV;
 
+        if (!try_module_get(idev->owner))
+                return -ENODEV;
+
         listener = kmalloc(sizeof(*listener), GFP_KERNEL);
-        if (!listener)
-                return -ENOMEM;
+        if (!listener) {
+                ret = -ENOMEM;
+                goto err_alloc_listener;
+        }
 
         listener->dev = idev;
         listener->event_count = atomic_read(&idev->event);
         filep->private_data = listener;
 
         if (idev->info->open) {
-                if (!try_module_get(idev->owner))
-                        return -ENODEV;
                 ret = idev->info->open(idev->info, inode);
-                module_put(idev->owner);
+                if (ret)
+                        goto err_infoopen;
         }
 
-        if (ret)
-                kfree(listener);
+        return 0;
+
+err_infoopen:
+
+        kfree(listener);
+err_alloc_listener:
+
+        module_put(idev->owner);
 
         return ret;
 }
@@ -336,12 +346,11 @@ static int uio_release(struct inode *inode, struct file *filep)
         struct uio_listener *listener = filep->private_data;
         struct uio_device *idev = listener->dev;
 
-        if (idev->info->release) {
-                if (!try_module_get(idev->owner))
-                        return -ENODEV;
+        if (idev->info->release)
                 ret = idev->info->release(idev->info, inode);
-                module_put(idev->owner);
-        }
+
+        module_put(idev->owner);
+
         if (filep->f_flags & FASYNC)
                 ret = uio_fasync(-1, filep, 0);
         kfree(listener);
@@ -510,10 +519,7 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
                 return -EINVAL;
 
         if (idev->info->mmap) {
-                if (!try_module_get(idev->owner))
-                        return -ENODEV;
                 ret = idev->info->mmap(idev->info, vma);
-                module_put(idev->owner);
                 return ret;
         }