From: Li Zefan <lizefan@huawei.com>
To: Tejun Heo <tj@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
LKML <linux-kernel@vger.kernel.org>,
Cgroups <cgroups@vger.kernel.org>
Subject: [PATCH] cgroup: fail if monitored file and event_control are in different cgroup
Date: Mon, 18 Feb 2013 14:13:35 +0800 [thread overview]
Message-ID: <5121C68F.1000309@huawei.com> (raw)
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@huawei.com>
---
kernel/cgroup.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 65c8101..a41673c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3911,6 +3911,7 @@ 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;
@@ -3966,6 +3967,16 @@ 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;
--
1.8.0.2
next reply other threads:[~2013-02-18 6:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-18 6:13 Li Zefan [this message]
2013-02-18 10:24 ` [PATCH] cgroup: fail if monitored file and event_control are in different cgroup Kirill A. Shutemov
2013-02-18 17:32 ` Tejun Heo
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