HID: hidraw: fix window in hidraw_release

commit cb174681a9ececa6702f114b85bdf82144b6a5af upstream.

[ Backport to .32.y by Antonio Ospite <ospite@studenti.unina.it> ]

There is a window between hidraw_table check and its dereference.
In that window, the device may be unplugged and removed form the
system and we will then dereference NULL.

Lock that place properly so that either we get NULL and jump out or we
can work with real pointer.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 66579c0bf32821c7c418e2114fa524f9d896965f..5b57551233f4c52cb12283121c4dcbbe55bc9e54 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -211,11 +211,14 @@ static int hidraw_release(struct inode * inode, struct file * file)
        unsigned int minor = iminor(inode);
        struct hidraw *dev;
        struct hidraw_list *list = file->private_data;
+       int ret;
 
+       mutex_lock(&minors_lock);
        if (!hidraw_table[minor]) {
                printk(KERN_EMERG "hidraw device with minor %d doesn't exist\n",
                                minor);
-               return -ENODEV;
+               ret = -ENODEV;
+               goto unlock;
        }
 
        list_del(&list->node);
@@ -229,10 +232,12 @@ static int hidraw_release(struct inode * inode, struct file * file)
                        kfree(list->hidraw);
                }
        }
-
        kfree(list);
+       ret = 0;
+unlock:
+       mutex_unlock(&minors_lock);
 
-       return 0;
+       return ret;
 }
 
 static long hidraw_ioctl(struct file *file, unsigned int cmd,