releases/4.0.8/usb-gadget-f_fs-add-extra-check-before-unregister_gadget_item.patch

   1 From f14e9ad17f46051b02bffffac2036486097de19e Mon Sep 17 00:00:00 2001
   2 From: Rui Miguel Silva <rui.silva@linaro.org>
   3 Date: Wed, 20 May 2015 14:52:40 +0100
   4 Subject: usb: gadget: f_fs: add extra check before unregister_gadget_item
   5
   6 From: Rui Miguel Silva <rui.silva@linaro.org>
   7
   8 commit f14e9ad17f46051b02bffffac2036486097de19e upstream.
   9
  10 ffs_closed can race with configfs_rmdir which will call config_item_release, so
  11 add an extra check to avoid calling the unregister_gadget_item with an null
  12 gadget item.
  13
  14 Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
  15 Signed-off-by: Felipe Balbi <balbi@ti.com>
  16 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  17
  18 ---
  19  drivers/usb/gadget/function/f_fs.c |   10 ++++++++--
  20  1 file changed, 8 insertions(+), 2 deletions(-)
  21
  22 --- a/drivers/usb/gadget/function/f_fs.c
  23 +++ b/drivers/usb/gadget/function/f_fs.c
  24 @@ -3433,6 +3433,7 @@ done:
  25  static void ffs_closed(struct ffs_data *ffs)
  26  {
  27         struct ffs_dev *ffs_obj;
  28 +       struct f_fs_opts *opts;
  29
  30         ENTER();
  31         ffs_dev_lock();
  32 @@ -3446,8 +3447,13 @@ static void ffs_closed(struct ffs_data *
  33         if (ffs_obj->ffs_closed_callback)
  34                 ffs_obj->ffs_closed_callback(ffs);
  35
  36 -       if (!ffs_obj->opts || ffs_obj->opts->no_configfs
  37 -           || !ffs_obj->opts->func_inst.group.cg_item.ci_parent)
  38 +       if (ffs_obj->opts)
  39 +               opts = ffs_obj->opts;
  40 +       else
  41 +               goto done;
  42 +
  43 +       if (opts->no_configfs || !opts->func_inst.group.cg_item.ci_parent
  44 +           || !atomic_read(&opts->func_inst.group.cg_item.ci_kref.refcount))
  45                 goto done;
  46
  47         unregister_gadget_item(ffs_obj->opts->