From: Lars-Peter Clausen <lars@metafoo.de>
Date: Thu, 14 Apr 2016 15:01:17 +0000 (+0200)
Subject: usb: gadget: f_fs: Fix use-after-free
X-Git-Tag: v3.16.40~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0fbed614ccd7ab27d77bc129a9d8539181d7d275;p=thirdparty%2Fkernel%2Fstable.git

usb: gadget: f_fs: Fix use-after-free

commit 38740a5b87d53ceb89eb2c970150f6e94e00373a upstream.

When using asynchronous read or write operations on the USB endpoints the
issuer of the IO request is notified by calling the ki_complete() callback
of the submitted kiocb when the URB has been completed.

Calling this ki_complete() callback will free kiocb. Make sure that the
structure is no longer accessed beyond that point, otherwise undefined
behaviour might occur.

Fixes: 2e4c7553cd6f ("usb: gadget: f_fs: add aio support")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
[bwh: Backported to 3.16:
 - Adjust filename
 - We only use kiocb::private, not kiocb::ki_flags]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 4d6c0630f1f9a..e8bfead449bbd 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -669,7 +669,6 @@ static void ffs_user_copy_worker(struct work_struct *work)
 
 	usb_ep_free_request(io_data->ep, io_data->req);
 
-	io_data->kiocb->private = NULL;
 	if (io_data->read)
 		kfree(io_data->iovec);
 	kfree(io_data->buf);