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authorMarek Marczykowski-Górecki <marmarek@invisiblethingslab.com>2015-06-26 03:28:24 +0200
committerDavid Vrabel <david.vrabel@citrix.com>2015-06-30 16:57:32 +0100
commit30b03d05e07467b8c6ec683ea96b5bffcbcd3931 (patch)
treef53898fc4128087d1ba6d03365f76472a212eba0
parent6684fa1cdb1ebe804e9707f389255d461b2e95b0 (diff)
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>
-rw-r--r--drivers/xen/gntdev.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 67b9163db718..0dbb222daaf1 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -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);