* [PATCH] cgroup: fail if monitored file and event_control are in different cgroup
@ 2013-02-18 6:13 Li Zefan
2013-02-18 10:24 ` Kirill A. Shutemov
2013-02-18 17:32 ` Tejun Heo
0 siblings, 2 replies; 3+ messages in thread
From: Li Zefan @ 2013-02-18 6:13 UTC (permalink / raw)
To: Tejun Heo; +Cc: Kirill A. Shutemov, LKML, Cgroups
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] cgroup: fail if monitored file and event_control are in different cgroup
2013-02-18 6:13 [PATCH] cgroup: fail if monitored file and event_control are in different cgroup Li Zefan
@ 2013-02-18 10:24 ` Kirill A. Shutemov
2013-02-18 17:32 ` Tejun Heo
1 sibling, 0 replies; 3+ messages in thread
From: Kirill A. Shutemov @ 2013-02-18 10:24 UTC (permalink / raw)
To: Li Zefan; +Cc: Tejun Heo, LKML, Cgroups
On Mon, Feb 18, 2013 at 02:13:35PM +0800, Li Zefan wrote:
> 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>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] cgroup: fail if monitored file and event_control are in different cgroup
2013-02-18 6:13 [PATCH] cgroup: fail if monitored file and event_control are in different cgroup Li Zefan
2013-02-18 10:24 ` Kirill A. Shutemov
@ 2013-02-18 17:32 ` Tejun Heo
1 sibling, 0 replies; 3+ messages in thread
From: Tejun Heo @ 2013-02-18 17:32 UTC (permalink / raw)
To: Li Zefan; +Cc: Kirill A. Shutemov, LKML, Cgroups
On Mon, Feb 18, 2013 at 02:13:35PM +0800, Li Zefan wrote:
> 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>
Applied to cgroup/for-3.9.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-02-18 17:32 UTC | newest]
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2013-02-18 10:24 ` Kirill A. Shutemov
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