Commit 30b03d05 authored Jun 26, 2015 by Marek Marczykowski-Górecki Committed by David Vrabel Jun 30, 2015

xen/gntdevt: Fix race condition in gntdev_release()



While gntdev_release() is called the MMU notifier is still registered
and can traverse priv->maps list even if no pages are mapped (which is
the case -- gntdev_release() is called after all). But
gntdev_release() will clear that list, so make sure that only one of
those things happens at the same time.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

parent 6684fa1c

drivers/xen/gntdev.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -568,12 +568,14 @@ static int gntdev_release(struct inode inode, struct file flip)

		pr_debug("priv %p\n", priv);

		mutex_lock(&priv->lock);
		while (!list_empty(&priv->maps)) {
		map = list_entry(priv->maps.next, struct grant_map, next);
		list_del(&map->next);
		gntdev_put_map(NULL /* already removed */, map);
		}
		WARN_ON(!list_empty(&priv->freeable_maps));
		mutex_unlock(&priv->lock);

		if (use_ptemod)
		mmu_notifier_unregister(&priv->mn, priv->mm);