[PATCH 4.0 28/55] usb: gadget: f_fs: add extra check before unregister_gadget_item

Greg Kroah-Hartman
2015-07-08T08:11:50Z

From: Rui Miguel Silva <rui.silva@linaro.org>

commit f14e9ad17f46051b02bffffac2036486097de19e upstream.

ffs_closed can race with configfs_rmdir which will call config_item_release, so
add an extra check to avoid calling the unregister_gadget_item with an null
gadget item.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/gadget/function/f_fs.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3433,6 +3433,7 @@ done:
static void ffs_closed(struct ffs_data *ffs)
{
struct ffs_dev *ffs_obj;
+ struct f_fs_opts *opts;

ENTER();
ffs_dev_lock();
@@ -3446,8 +3447,13 @@ static void ffs_closed(struct ffs_data *
if (ffs_obj->ffs_closed_callback)
ffs_obj->ffs_closed_callback(ffs);

- if (!ffs_obj->opts || ffs_obj->opts->no_configfs
- || !ffs_obj->opts->func_inst.group.cg_item.ci_parent)
+ if (ffs_obj->opts)
+ opts = ffs_obj->opts;
+ else
+ goto done;
+
+ if (opts->no_configfs || !opts->func_inst.group.cg_item.ci_parent
+ || !atomic_read(&opts->func_inst.group.cg_item.ci_kref.refcount))
goto done;

unregister_gadget_item(ffs_obj->opts->