From b876e14888bdafa112c3265e6420543fa74aa709 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= Date: Fri, 26 Jun 2015 02:16:49 +0200 Subject: [PATCH] xen/grant: fix race condition in gntdev_release MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Organization: Invisible Things Lab Cc: Marek Marczykowski-Górecki While gntdev_release is called, MMU notifier is still registered and will 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 --- drivers/xen/gntdev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 8927485..4bd23bb 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); + spin_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)); + spin_unlock(&priv->lock); if (use_ptemod) mmu_notifier_unregister(&priv->mn, priv->mm); -- 1.9.3