Patch "usb: gadget: f_fs: add extra check before unregister_gadget_item" has been added to the 4.0-stable tree

Patch "usb: gadget: f_fs: add extra check before unregister_gadget_item" has been added to the 4.0-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    usb: gadget: f_fs: add extra check before unregister_gadget_item

to the 4.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-gadget-f_fs-add-extra-check-before-unregister_gadget_item.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From f14e9ad17f46051b02bffffac2036486097de19e Mon Sep 17 00:00:00 2001
From: Rui Miguel Silva <rui.silva@linaro.org>
Date: Wed, 20 May 2015 14:52:40 +0100
Subject: usb: gadget: f_fs: add extra check before unregister_gadget_item

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->


Patches currently in stable-queue which might be from rui.silva@linaro.org are

queue-4.0/usb-gadget-f_fs-fix-check-in-read-operation.patch
queue-4.0/usb-gadget-f_fs-add-extra-check-before-unregister_gadget_item.patch