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>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 8c030d9dd0ddb61b3e63cf9db68759c1a8801726..b88f6b3235f83ddcbc1523b3faac18023b753b91 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -196,11 +196,14 @@ 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);
@@ -211,10 +214,12 @@ static int hidraw_release(struct inode * inode, struct file * file)
                else
                        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,