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authorMarek Marczykowski-Górecki <marmarek@invisiblethingslab.com>2015-06-26 03:28:24 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-08-16 20:51:39 -0700
commit292f53675e097ca807df744fb6fd39211a134bf7 (patch)
treef7388c05f9ff28777ec7906097a62322adeec79d
parent3f2c206ae6f9e1005ac7f092e8d65c17307a0d59 (diff)
xen/gntdevt: Fix race condition in gntdev_release()
commit 30b03d05e07467b8c6ec683ea96b5bffcbcd3931 upstream. 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> Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 3c8803feba26..474d11499d0e 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -534,12 +534,14 @@ 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);