This is a note to let you know that I've just added the patch titled
Subject: USB: g_file_storage: fix use-after-free bug when closing files
to my gregkh-2.6 tree. Its filename is
usb-g_file_storage-fix-use-after-free-bug-when-closing-files.patch
This tree can be found at
http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/
>From stern@xxxxxxxxxxxxxxxxxxx Tue Apr 21 17:09:05 2009
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 16 Apr 2009 15:37:28 -0400 (EDT)
Subject: USB: g_file_storage: fix use-after-free bug when closing files
To: Greg KH <greg@xxxxxxxxx>
Cc: USB list <linux-usb@xxxxxxxxxxxxxxx>, <stable@xxxxxxxxxx>
Message-ID: <Pine.LNX.4.44L0.0904161535110.2718-100000@xxxxxxxxxxxxxxxxxxxx>
This patch (as1231) fixes a use-after-free bug in g_file_storage. A
device's name may not be available after the device is unregistered,
even if the device structure itself is still allocated. Since
close_backing_file() prints a LUN's name for debugging, it shouldn't
be called after the LUN has been unregistered.
That whole area needed to be cleaned up; the backing files were
getting closed in a couple of different places. The patch fixes
things so that they get closed in just one place, as part of the
unbind procedure, immediately before the LUN is unregistered.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/usb/gadget/file_storage.c | 20 ++++----------------
1 file changed, 4 insertions(+), 16 deletions(-)
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -738,7 +738,6 @@ static struct fsg_dev *the_fsg;
static struct usb_gadget_driver fsg_driver;
static void close_backing_file(struct lun *curlun);
-static void close_all_backing_files(struct fsg_dev *fsg);
/*-------------------------------------------------------------------------*/
@@ -3593,12 +3592,10 @@ static int fsg_main_thread(void *fsg_)
fsg->thread_task = NULL;
spin_unlock_irq(&fsg->lock);
- /* In case we are exiting because of a signal, unregister the
- * gadget driver and close the backing file. */
- if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags)) {
+ /* If we are exiting because of a signal, unregister the
+ * gadget driver. */
+ if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags))
usb_gadget_unregister_driver(&fsg_driver);
- close_all_backing_files(fsg);
- }
/* Let the unbind and cleanup routines know the thread has exited */
complete_and_exit(&fsg->thread_notifier, 0);
@@ -3703,14 +3700,6 @@ static void close_backing_file(struct lu
}
}
-static void close_all_backing_files(struct fsg_dev *fsg)
-{
- int i;
-
- for (i = 0; i < fsg->nluns; ++i)
- close_backing_file(&fsg->luns[i]);
-}
-
static ssize_t show_ro(struct device *dev, struct device_attribute *attr, char *buf)
{
@@ -3845,6 +3834,7 @@ static void /* __init_or_exit */ fsg_unb
if (curlun->registered) {
device_remove_file(&curlun->dev, &dev_attr_ro);
device_remove_file(&curlun->dev, &dev_attr_file);
+ close_backing_file(curlun);
device_unregister(&curlun->dev);
curlun->registered = 0;
}
@@ -4190,7 +4180,6 @@ autoconf_fail:
out:
fsg->state = FSG_STATE_TERMINATED; // The thread is dead
fsg_unbind(gadget);
- close_all_backing_files(fsg);
complete(&fsg->thread_notifier);
return rc;
}
@@ -4284,7 +4273,6 @@ static void __exit fsg_cleanup(void)
/* Wait for the thread to finish up */
wait_for_completion(&fsg->thread_notifier);
- close_all_backing_files(fsg);
kref_put(&fsg->ref, fsg_release);
}
module_exit(fsg_cleanup);
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
