HID: hidraw, fix a NULL pointer dereference in hidraw_ioctl

commit d20d5ffab92f00188f360c44c791a5ffb988247c upstream.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: [<ffffffffa02c66b4>] hidraw_ioctl+0xfc/0x32c [hid]
[...]

This is reproducible by disconnecting the device while userspace does
ioctl in a loop and doesn't check return values in order to exit the
loop.

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

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index cdd136942bcaa9e1435b1d2efc5444bf6f3317fc..3b53475a2b3d82ce77738fc8de43f3e3935e11ca 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -237,11 +237,16 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
        struct inode *inode = file->f_path.dentry->d_inode;
        unsigned int minor = iminor(inode);
        long ret = 0;
-       /* FIXME: What stops hidraw_table going NULL */
-       struct hidraw *dev = hidraw_table[minor];
+       struct hidraw *dev;
        void __user *user_arg = (void __user*) arg;
 
        lock_kernel();
+       dev = hidraw_table[minor];
+       if (!dev) {
+               ret = -ENODEV;
+               goto out;
+       }
+
        switch (cmd) {
                case HIDIOCGRDESCSIZE:
                        if (put_user(dev->hid->rsize, (int __user *)arg))
@@ -314,6 +319,7 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
 
                ret = -ENOTTY;
        }
+out:
        unlock_kernel();
        return ret;
 }