[ 3.5.y.z extended stable ] Patch "cgroup: fail if monitored file and event_control are in" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Wed Oct 2 15:03:53 UTC 2013
This is a note to let you know that I have just added a patch titled
cgroup: fail if monitored file and event_control are in
to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 1f5e6adc5d62e92ad68456c439d762bf6161542a Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan at huawei.com>
Date: Mon, 18 Feb 2013 14:13:35 +0800
Subject: [PATCH] cgroup: fail if monitored file and event_control are in
different cgroup
commit f169007b2773f285e098cb84c74aac0154d65ff7 upstream.
If we pass fd of memory.usage_in_bytes of cgroup A to cgroup.event_control
of cgroup B, then we won't get memory usage notification from A but B!
What's worse, if A and B are in different mount hierarchy, we'll end up
accessing NULL pointer!
Disallow this kind of invalid usage.
Signed-off-by: Li Zefan <lizefan at huawei.com>
Acked-by: Kirill A. Shutemov <kirill at shutemov.name>
Signed-off-by: Tejun Heo <tj at kernel.org>
Cc: Weng Meiling <wengmeiling.weng at huawei.com>
Cc: Li Zefan <lizefan at huawei.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
kernel/cgroup.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3b3fa5b..7720f52 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3712,6 +3712,7 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
struct cgroup_event *event = NULL;
+ struct cgroup *cgrp_cfile;
unsigned int efd, cfd;
struct file *efile = NULL;
struct file *cfile = NULL;
@@ -3767,6 +3768,16 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
goto fail;
}
+ /*
+ * The file to be monitored must be in the same cgroup as
+ * cgroup.event_control is.
+ */
+ cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
+ if (cgrp_cfile != cgrp) {
+ ret = -EINVAL;
+ goto fail;
+ }
+
if (!event->cft->register_event || !event->cft->unregister_event) {
ret = -EINVAL;
goto fail;
--
1.8.3.2
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