This is a note to let you know that I've just added the patch titled
usb: gadget: f_fs: Fix use-after-free
to the 4.4-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-fix-use-after-free.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 38740a5b87d53ceb89eb2c970150f6e94e00373a Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@xxxxxxxxxx>
Date: Thu, 14 Apr 2016 17:01:17 +0200
Subject: usb: gadget: f_fs: Fix use-after-free
From: Lars-Peter Clausen <lars@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/f_fs.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -646,6 +646,7 @@ static void ffs_user_copy_worker(struct
work);
int ret = io_data->req->status ? io_data->req->status :
io_data->req->actual;
+ bool kiocb_has_eventfd = io_data->kiocb->ki_flags & IOCB_EVENTFD;
if (io_data->read && ret > 0) {
use_mm(io_data->mm);
@@ -657,13 +658,11 @@ static void ffs_user_copy_worker(struct
io_data->kiocb->ki_complete(io_data->kiocb, ret, ret);
- if (io_data->ffs->ffs_eventfd &&
- !(io_data->kiocb->ki_flags & IOCB_EVENTFD))
+ if (io_data->ffs->ffs_eventfd && !kiocb_has_eventfd)
eventfd_signal(io_data->ffs->ffs_eventfd, 1);
usb_ep_free_request(io_data->ep, io_data->req);
- io_data->kiocb->private = NULL;
if (io_data->read)
kfree(io_data->to_free);
kfree(io_data->buf);
Patches currently in stable-queue which might be from lars@xxxxxxxxxx are
queue-4.4/usb-gadget-f_fs-fix-use-after-free.patch
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