Driver core fix for 5.13-rc6

Here is a single debugfs fix for 5.13-rc6.
 
 It fixes a bug in debugfs_read_file_str() that showed up in 5.13-rc1.
 
 It has been in linux-next for a full week with no reported problems.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fix from Greg KH:
 "A single debugfs fix for 5.13-rc6, fixing a bug in
  debugfs_read_file_str() that showed up in 5.13-rc1.

  It has been in linux-next for a full week with no
  reported problems"

* tag 'driver-core-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  debugfs: Fix debugfs_read_file_str()

fs/debugfs/file.c

@@ -893,7 +893,7 @@ ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf,
 
 	copy[copy_len] = '\n';
 
-	ret = simple_read_from_buffer(user_buf, count, ppos, copy, copy_len);
+	ret = simple_read_from_buffer(user_buf, count, ppos, copy, len);
 	kfree(copy);
 
 	return ret;