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[added,to,the,3.18,stable,tree] usb: gadget: f_fs: add extra check before unregister_gadget_item

Message ID 1436795065-27444-29-git-send-email-sasha.levin@oracle.com
State New
Headers show

Commit Message

Sasha Levin July 13, 2015, 1:44 p.m. UTC 
From: Rui Miguel Silva <rui.silva@linaro.org>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
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Patch

===============

[ Upstream commit f14e9ad17f46051b02bffffac2036486097de19e ]

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: Sasha Levin <sasha.levin@oracle.com>
---
 drivers/usb/gadget/function/f_fs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 63314ed..ab9b7ac 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3400,6 +3400,7 @@  done:
 static void ffs_closed(struct ffs_data *ffs)
 {
 	struct ffs_dev *ffs_obj;
+	struct f_fs_opts *opts;
 
 	ENTER();
 	ffs_dev_lock();
@@ -3413,8 +3414,13 @@  static void ffs_closed(struct ffs_data *ffs)
 	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->