[3.16.y-ckt stable] Patch "xen/gntdevt: Fix race condition in gntdev_release()" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Thu Sep 3 12:32:44 UTC 2015
This is a note to let you know that I have just added a patch titled
xen/gntdevt: Fix race condition in gntdev_release()
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt17.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From f27f75ca7aab35143daf6ab708eefef37a119c0b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
<marmarek at invisiblethingslab.com>
Date: Fri, 26 Jun 2015 03:28:24 +0200
Subject: xen/gntdevt: Fix race condition in gntdev_release()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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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 at invisiblethingslab.com>
Signed-off-by: David Vrabel <david.vrabel at citrix.com>
Cc: Ian Campbell <ian.campbell at citrix.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/xen/gntdev.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index b7f028a8f542..91cc44611062 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -529,12 +529,14 @@ 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);
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